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Homoleptic complexes of cobalt(0) and nickel(0,I) with 1,1′- bis(diphenylphosphino)ferrocene (dppf): Synthesis and characterization
Reduction of Co(dppf)Cl2 with 2 equiv of sodium naphthalenide in THF, in the presence of dppf, affords the homoleptic complex Co(dppf) 2, 1, isolated in 65% yield as a brick red solid, extremely air sensitive. In solution, under inert atmosphere, 1 slowly decomposes into Co and dppf, following a first-order kinetic law (t1/2 = 21 h at 22°C). Similarly to the Rh and Ir congeners, 1 undergoes a one-electron reversible reduction to [Co(dppf)2]-. Attempts to obtain this d 10 species by chemical as well as electrochemical reduction of 1 lead to the hydride HCo(dppf)2, 2, as the only product that can be isolated. Reduction of Ni(dppf)Cl2 with sodium in the presence of dppf and catalytic amounts of naphthalene affords Ni(dppf)2, 3, isolated in 60% yield as a yellow air stable solid. The stoichiometric oxidation of 3 with [FeCp2]PF6 forms the d9 complex [Ni(dppf)2]PF6, 4, which represents the second example of a structurally characterized Ni(I) complex stabilized by phosphines. A single-crystal X-ray analysis shows for the metal a distorted tetrahedral environment with a dihedral angle defined by the planes containing the atoms P(1), Ni, P(2) and P(3), Ni, P(4) of 78.2° and remarkably long Ni-P bond distances (2.342(3)-2.394(3) A). The EPR spectroscopic properties of 1 (at 106 K in THF) and 4 (at 7 K in 2-methyl-THF) have been examined and g tensor values measured (1, gx = 2.008, gy = 2.182, gz = 2.326; 4, gx = 2.098, gy = 2.113, gz = 2.332). A linear dependence between the hyperfine constants and the Ni-P bond distances has been evidenced. Finally, the change with time of the EPR spectrum of 4 indicates that it very slowly releases dppf.
Pilloni, Giuseppe,Toffoletti, Antonio,Bandoli, Giuliano,Longato, Bruno
p. 10321 - 10328
(2006)
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Reactivity of an early-late heterobimetallic complex toward phosphines: Synthesis, structure, and reactivity of a cationic tantalum-palladium compound with a free cyclopentadienyl counteranion
Treatment of Cp2Ta(CH2)(CH3) with CpPd-(C3H5) led to Cp2Ta(μ-CH2)2PdCp(1). Reaction of 1 with 1 equiv of either PMe3 or P(OMe)3 in CH2Cl2 resulted in the formation of Cp2Ta(μ-CH2)2Pd(PR3)(Cl) (R = Me, 2; R = OMe, 3) and 0.5 equiv of Cp2(CH2). The reaction of 1 with 2 equiv of PMe3 or P(OMe)3 or 1 equiv of Me2P(CH2)2PMe2 (DMPE) led to the isolation of [Cp2-Ta(μ-CH2)2PdL2]Cl (L2 = 2 PMe3, 4; L2 = 2 P(OMe)3, 5; L2 = DMPE, 6). Addition of P(OMe)3 to 1 in CH3CN gave the product Cp2Ta(μ-CH2)2Pd(P(OMe)3)(CH 2CN) (7). Each of these reactions of 1 with phosphorus compounds implicates the intermediacy of free cyclopentadienyl onion. In support of this hypothesis, the stable naked Cp complex [Cp2Ta(μ-CH2)2Pd(DMPE)]Cp (8) was isolated from the reaction of 1 with DMPE in CH3CN and was characterized by X-ray crystallography. The shortest distance between the free anionic Cp group and the bimetallic fragment in 8 is 3.46(3) A. Addition of FeCl2 to 8 resulted in the formation of 1/2 equiv of Cp2Fe and 6. Treatment of 8 with 1,2-dibromoethane led to the quantitative formation of 1/2 equiv of spiro[2.4]hepta-4,6-diene together with the bromide salt of 8.
Butts, Matthew D.,Bergman, Robert G.
p. 4269 - 4271
(1993)
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Unusual reactivities of (μ-η2:η2-FP-CC-H)Co2(CO)6, the adducts of FP-CC-H to Co2(CO)8: photolysis, thermolysis and reduction with hydrosilanes giving polynuclear complexes, (CP)2Fe2Co3(μ5-C=CH)(CO)10, (μ-CH=CH)3-C)Co3(CO)9>2 and CpFeCo3(μ-C=CH2)(CO)9
The properties and reactivities of (μ-η2:η2-FP-CC-H)Co2(CO)6 (3) C-H adducts to Co2(CO)8: 3a (FP = Fp), 3b (FP = Fp*)> have been compared with those of alkyne adducts (μ-η2:η2-R-CC-R)Co2(CO)6 and the Ph analogue (μ-η2:η2-Fp-CC-Ph)Co2(CO)6 (5).Compound 3 has been shown to serve as a building block for polynuclear complexes. 13CO-labelling experiments on 3a and 5 have revealed an intramolecular exchange between the Fe-CO and Co-CO ligands.Photolysis of 3a, b produces pentanuclear clusters (CP)2Fe2Co3(μ5-C=CH)(CO)10 (11a,b), respectively, via an apparent addition reaction of a (CP)FeCo(CO)n fragment to 3.On the other hand, thermolysis of 3a gives the Fe-free hexacobalt cluster compound (μ-C=CH)3-C)Co3(CO)9>2 (13) which consists of two alkylidyne tricobalt units linked by the CH=CH bridge, whereas 3b is thermolyzed to give the Fe-Co dimer without the C2H ligand, Cp*Fe(CO)(μ-CO)2Co(CO)3 (14), in addition to the photolysis product 11b.Reduction of 3 with hydrosilanes gives a mixture containing 1,2-disilylethylene (16) and the tetranuclear μ-vinylidene cluster CpFeCo3(μ4-C=CH2)(CO)9 (12) formally by way of hydrosilylation and hydrometallation (with a HCo(CO)n species) of the C2H ligand, respectively.In the case of the Pauson-Khand reaction and catalytic cyclotrimerization 3a exhibits reactivities similar to alkyne adducts to give the tricyclic cyclopentenone derivatives 18 (from norbornene and norbornadiene) and triphenylbenzenes, respectively. Key words: Iron; Cobalt; Carbonyl; Polynuclear
Akita, Munetaka,Terada, Masako,Ishii, Naomi,Hirakawa, Hideki,Moro-oka, Yoshihiko
p. 175 - 186
(1994)
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Oxidatively induced nucleophilic capture vs. degradation of cyclopentadienyl iron derivatives of simple carboxylic acids and of α-amino acids. A comparative study
The electrochemical behaviour and the chemical oxidation of various cyclopentadienyl iron complexes of simple carboxylic acids and of amino-protected α-amino acids have been studied in relation to several factors including the nature of the ligands on the metal (Cp, Cp*, CO, PPh3), the nature of the oxidizing agent (one-electron oxidants such as Cu(OTf)2, FcOTf and CAN or a two-electron oxidant such as NBS) and the medium effects (especially the presence or absence of nucleophilic species).With simple carboxylic acid derivatives either homolytic dissociation (leading to alkyl radicals) or nucleophilic capture of the first-formed iron radical cations is observed, depending on the reaction conditions.With α-amino acid derivatives, an oxidative degradation to aldehyde is observed invariably, which is likely to proceed through the successive and transient formation of N-acyl α-amino radicals and N-acyl iminium ions.
Amiens, C.,Balavoine, G.,Guibe, F.
p. 207 - 219
(1993)
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Multinuclear complexes derived from ferrocenylphosphines and triruthenium dodecacarbonyl
Pyrolysis of Ru3(CO)11(PFc2Ph) in hexanes for 15 h gave the trinuclear cluster Ru3(CO)8-(μ-CO)(μ-H)[μ-η 3-(η5-C5H3PFcPh)Fe(η 5-C5H5)] (11) in 20% yield. Pyrolysis of Ru3(CO)12 with PFc2Ph in octane for 3.5 h gave the tetranuclear cluster Ru4(CO)11(μ3-PFc)(μ-η 1:η5-C5H4 (12) in 12% yield and the previously known 8, Ru4(CO)10(μ-CO)μ4-PFc)(μ 4-C6H4), in 10% yield: the mild conditions are noteworthy. Pyrolysis of Ru3(CO)12 with PEt2Fc in octane for 18 h gave the hexanuclear cluster complexes Ru6C(CO)14(μ-PEt2)2 (13) and Ru6C(CO)13(μ-PEt2)-(η5-C 5H5) (14) in 15% and 25% yields, respectively, and the pentanuclear derivative Ru5-(CO)9(μ-CO)(η6-C6H 6)2(μ4-PEt) (15) (low yield). Pyrolysis of Ru3(CO)12 with PEtFc2 in toluene for 10 h gave the pentanuclear cluster Ru5(CO)12(μ4-PEt)(η6-C 7H8) (16) in ～5% yield. Crystal data: 8, monoclinic, space group P21/c, a = 14.725(3) A?, b = 9.024(2) A?, c = 22.719(1) A?, β = 92.078(8)°, Z = 4; 11, triclinic, P1, a = 12.7671(9) A?, b = 13.284(1) A?, c = 10.2212(8) A?, α = 93.006(6)°, β = 98.561(6)°, γ = 83.665(6)°, Z = 2; 12, monoclinic, space group P21/c, a = 10.463(2) A?, b = 16.412(1) A?, c = 17.903(2) A?, β = 103.85(1)°, Z = 4; 13, monoclinic, space group C2/c, a = 12.566(2) A?, b = 16.326(2) A?, c = 17.001(2) A?, β = 105.43(1)°, Z = 4; 14, monoclinic, space group P21/c,a = 12.638(2) A?, b = 9.911(3) A?, c = 24.743(5) A?, β = 91.33-(2)°, Z = 4; 15, orthorhombic, space group Cmc21, a = 16.239(1) A?, b = 13.754(2) A?, c = 11.895(2) A?, Z = 4; 16, monoclinic, space group C2/c, a = 31.831(3) A?, b = 9.904(2) A?, c = 17.536(2) A?, β = 99.36(1)°, Z = 8. The structures were solved by direct or Patterson methods and were refined by full-matrix least-squares procedures to R = 0.042, 0.024, 0.027, 0.024, 0.028, 0.032, and 0.026 for 4943, 8583, 5279, 3650, 6357, 1302, and 5711 reflections with I ≥ 3σ(I), respectively.
Zheng, Tu Cai,Cullen, William R.,Rettig, Steven J.
p. 3594 - 3604
(1994)
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AZOLE ANIONS AS ONE-ELECTRON REDUCERS OF FERRICINIUM SALTS
Azole anions are capable of reducing ferricinium cation to ferrocene in solution at room temperature.Th formation of azolyl radicals under these conditions is detected.
Babin, V. N.,Belousov, Yu. A.,Lyatifov, I. R.,Materikova, R. B.,Gumenyuk, V. V.
p. C11 - C12
(1981)
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Ferrocenylaluminum-pyridine adducts, lithium tetra(ferrocenyl)alanate, and the molecular structure of tri(ferrocenyl)aluminum-pyridine
Aluminum compounds with up to four ferrocenyl groups (Fc) linked to aluminum were prepared and characterized in solution by NMR spectroscopy (1H, 13C, 27Al NMR), and in one case, tri(ferrocenyl)aluminum-pyridine Fc3/
Wrackmeyer, Bernd,Klimkina, Elena V.,Ackermann, Tamara,Milius, Wolfgang
p. 3941 - 3948
(2009)
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THE APPLICATION OF 13C AND 1H NMR SPECTROSCOPY TO THE INVESTIGATION OF THE DINITROGEN FIXATION PROCESS IN THE SYSTEM (η-C5H5)2TiCl2-Mg
The N2 reduction reaction in the system (η-C5H5)2TiCl2-Mg in tetrahydrofuran was examined.The 13C and 1H NMR results as well as the chemical properties of the products formed revealed that the reaction yielded a mixture of compounds in which the titanium atom was bonded both to the μ-(η5: η5-fulvalene) ligand and to the cyclopentadienyl ligands.In this system dinitrogen undergoes reduction to N3-, which then forms M3N bridges (M = Ti, Mg).The nitride nitrogen may readily be oxidized to imide nitride N-1, which may react further, e.g. with carbon monoxideto produce isocyanates, or, with excess oxidizing agent N2.THF in this system undergoes polymerisation.In addition, a - OC4H9 alkoxy group is formed which makes the substitution of the cyclopentadienyl group bonded to the titanium atoms possible.
Sobota, Piotr,Janas, Zofia
p. 35 - 44
(1983)
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Oxidation and Protonation of Transition Metal Hydrides: Role of an Added Base as Proton Shuttle and Nature of Protonated Water in Acetonitrile
The Cp2Fe+ oxidation and the protonation of CpMoH(CO)2L (L: PPh3, 1; PMe3, 2) in MeCN have been investigated. In the dry solvent, the oxidation of both compounds consumes 1 mol of oxidant/mol of hydride with production of [CpMo(CO)2L(MeCN)]+ (L: PPh2, [3]+; PMe3, [4]+) and H2. The stoichiometry changes toward the consumption of 2 mol of oxidant in the presence of excess water when the oxidizing equivalents are added rapidly, either chemically or electrochemically. However, 1 oxidizing equiv is again sufficient to consume the hydride material completely under conditions of slow oxidation. Under comparable conditions, the more basic 2 leads to a lower [ox]/M-H stoichiometry. Protonation of 1 and 2 with HBF4·Et2O in dry MeCN results in rapid H2 evolution and formation of [3]+ and [4]+, respectively, whereas the presence of excess water suppresses the H2 evolution and gives rise to protonated water. However, this process is followed by slow and irreversible delivery of the proton back to 1 or 2 to afford [CpMoH2(CO)2L]+, which ultimately decomposes to [3]+ or [4]+ and H2. The dihydride complex is too unstable to be isolated, even when the protonation of 1 or 2 is carried out in a noncoordinating solvent. The proton delivery is faster for the more basic 2 and slower for the less basic 1. Thus, water operates as a proton shuttle , whose speed depends on the basicity difference between the hydride complex and water. The identity of the protonated water in MeCN as [H(H2O)32]+ is suggested by an independent 1H-NMR experiment in CD3CN.
Alessandra Quadrelli,Kraatz, Heinz-Bernhard,Poli, Rinaldo
p. 5154 - 5162
(1996)
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δ-Ferrocenyl-Komplexe des Rutheniums
The reactions of lithioferrocene (fcLi) and 1,1'-dilithioferrocene (FcLi2) with the halfsandwich ruthenium complexes CpRu(CO)2Cl, Cp*Ru(CO)2Cl and (C6Me6)Ru(CO)Cl2 have been used to prepare the ferrocenyl compounds CpRu(CO)2Fc (1), Cp*Ru(CO)2Fc (2) and (C6Me6)Ru(CO)(Cl)Fc (3), as well as the ferrocenylene compounds 2fc (4) and *Ru(CO)2>2fc (5), respectively. Photodecarbonylation of 1 and 2 in the presence of two-electron ligands (L = CNtBu (a), PPh3 (b), PMe3 (c)) leads to chiral complexes of the type Cp(*)Ru(CO)(L)Fc (1a-c, 2a-c); in the case of L = CNtBu, further CO-substitution takes place to give Cp(*)Ru(CNtBu)2Fc (1d, 2d).Photo-induced reaction of 3 with excess trimethylphosphane, PMe3 (c), produces the octahedral complex mer- (6), whereas organolithiums (nBuLi and p-TolLi, but not FcLi) react with 3 to give (C6Me6)Ru(CO)(R)Fc (R = nBu (7a), p-Tol (7b)).Oxidation of 1, 2 and 3 by AgBF4 leads to paramagnetic salts such as (*)Ru(CO)2Fc>BF4 (1e, 2e) and BF4 (3e).All new complexes were characterized by IR, 1H and 13C NMR, and mass spectroscopy; the Cp and Cp* compounds were also studied by cyclovoltammetry.
Herberhold, Max,Feger, Wolfgang,Koelle, Ulrich
p. 333 - 350
(1992)
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Electrochemical and structural characterization of cis-and trans-[Cp(CO)Ru(μ-As(C6H5)2)]2, isomers that undergo two-electron-transfer oxidations
The structures and oxidations of the cis and trans isomers of the doubly bridged dinuclear species [Cp(CO)Ru(μ-AsPh2)]2 (Ph = C6H5) have been studied by X-ray crystallography, electrochemistry, and IR and NMR spectroscopies. Each complex oxidizes in a single two-electron voltammetric process, the E1/2 values being -0.36 V for the cis isomer (1) and -0.30 V for the trans isomer (2) in CH2Cl2/0.1 M [NBu4][PF6] (referenced to ferrocene). These are apparently the first comparative redox potentials published for cis and trans isomers of bridged dinuclear organometallic complexes. Oxidation of 1 to 12+ was cleanly accomplished either by electrolysis or by oxidation of 1 by 2 equiv of ferrocenium, allowing isolation of the dication. The split carbonyl absorptions in the IR spectra of 12+ (νCO = 2032, 2050 cm-1) are consistent with formation of a Ru-Ru bond in the oxidation reaction. The electrode reaction 1/1+ + e- is much slower than the reaction 1+/12+ + e-, implying that the metal-metal bond is formed in the former process. This conclusion is supported by the observation that the inner-sphere activation barrier, ΔG?, is about 8.5 kcal/mol, close to that (～10 kcal/ mol) estimated for a one-electron oxidation involving formation and cleavage of a Ru-Ru bond. The electron-transfer (ET) activation barrier is higher in these Ru complexes than in analogous Fe complexes, which are known to undergo large ET-induced changes in metal-metal bond lengths, most likely because M-M bond strengths are larger when M = Ru than when M = Fe.
DiMaio, Anthony-Joseph,Rheingold, Arnold L.,Chin, Teen T.,Pierce, David T.,Geiger, William E.
p. 1169 - 1176
(1998)
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Chemistry of cyclopentadienyliron dicarbonyl dimer and ferrocene in zeolite Y cavities: Anchoring organometallic fragments into microporous solids
The intracavity chemistry of [CpFe(CO)2]2 (1) and ferrocene in different acid forms of zeolite Y has been studied with EXAFS, in situ FTIR, and TPD-MS spectroscopies. Depending on the stoichiometry of zeolite protons vs the amount of
Moller,Borvornwattananont,Bein
p. 4562 - 4571
(1989)
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An electrochemical study of the reduction of mono- and bis(iron) cyclophane complexes
The electrochemical reduction of six [(η5-C5H5)Fe(η 6-cyclophane)]+PF6- and four {[(η5-C5H5)Fe] 2(cyclophane)}2+(PF6/
Bowyer, Walter J.,Geiger, William E.,Boekelheide, Virgil
p. 1079 - 1086
(1984)
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An improved photochemical synthesis of azaferrocene
A new synthesis of azaferrocene, (η5-C4H4N)(η5-C5H5)Fe, involving photo-substitution of iodide in (η5-C5H5)Fe(CO)2I by the η1-pyrrolyl ligand, followed by decarbonylation of the resulting dicarbonyl η1-pyrrolyl complex, is described.The mechanism of the former reaction is discussed in terms of the photo-induced SRN1-type chain process.
Zakrzewski, Janusz,Giannotti, Charles
p. 175 - 179
(1990)
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Little, W. F.,Koester, R. C.,Eisenthal, R.
p. 1435 - 1436
(1960)
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Synthesis and characterization of oxidized W6S8L6 clusters
Cationic [W6S8L6]PF6 (L = PEt3 (3), 4-tert-butylpyridine (4)) clusters were successfully synthesized and isolated for the first time by reacting the corresponding neutral W6S8L6 (L = PEt3 (1), 4-tert-butylpyridine (2)) clusters with [Cp2Fe]PF6 as the oxidant. The products 3 and 4 were characterized by NMR spectroscopy, mass spectroscopy, and X-ray crystallography (only for 3) and shown to be the desired oxidized W6S8 clusters with a metal electron count of 19. Magnetic property studies showed that they are paramagnetic compounds with S = 1/2. Their chemical properties and stability are also reported. Crystal data for 3·2THF: space group, R3 (No. 148); a = 13.91170(10) A; c = 32.4106(2) A; Z = 3.
Hill,Jin,Zhou,Venkataraman,DiSalvo
p. 2660 - 2665
(2001)
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The synthesis, aromaticity, and NMR properties of [14]annulene fused organometallics. Determination of the effective bond localizing ability ('relative aromaticity') and diamagnetic anisotropy of several organometallic moieties
The aromatic ring current probe, the bridged [14]annulene dimethyldihydropyrene, 1, is used to investigate the bond localization effects of the organometallic species tricarbonylchromiumbenzene, 37, hexamethylbenzenerutheniumbenzene, 38, tricarbonylmanganesecyclopentadienyl, 40, and pentamethylcyclopentadienylrutheniumcyclopentadienyl, 39, when fused to the annulene. Benzo[a]dimethyldihydropyrene 2 was converted to the two isomers of its tricarbonylchromium complex, 9 and 10, in 60% yield using ligand exchange with naphthalene and to its hexamethylbenzene-ruthenium complexes 11 and 12 with [RuCl2(HMB)]2 and AgBF4. The cyclopentadienide fused dihydropyrene 5 was synthesized from dimethyldihydropyrene 1 in eight steps, and then on reaction with pentacarbonyl manganese bromide gave the tricarbonylmanganese complex of 5, as two isomers 28 and 29 in 61% yield, and with (Cp*RuCl2)(n) gave 70% yield of the dihydropyrene annelated ruthenocene isomers 26 and 27. Bis(tricarbonylchromium) complexes 32-34 were obtained in 50% yield from the dibenzannulene 30. The 1H NMR spectra for each complex were analyzed in detail with regard to ring current shielding of the internal methyl protons and ring current deshielding of the external protons. The McGlinchey equation was used to remove diamagnetic anisotropy effects, and the resultant chemical shift values were consistent with coupling constant results, which together yielded bond fixation data of the annulene, caused by the organometallic. The relative bond fixing ability of the organometallics was found to be in the order: Cp-Ru-Cp* > benzene-Ru2+-(HMB) > Cp-Mn(CO)3 > benzene-Cr(CO)3 > benzene. Alternance parameter evidence is presented that the complexes are aromatic, and the authors discuss the relative aromaticity of the complexes to benzene.
Mitchell, Reginald H.,Chen, Yongsheng,Khalifa, Nasr,Zhou, Pengzu
p. 1785 - 1794
(1998)
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Sequential Friedel-Crafts diacetylation of ferrocene: Interannular proton transfers as a mechanistic probe
(Pentadeuteriocyclopentadienyl)cyclopentadienyliron(II), 4, was prepared by the sequential addition of lithium tris(trimethylsilyl)cyclopentadienide and lithium pentadeuteriocyclopentadienide to FeBr2 followed by fluoride-induced removal of the trimethylsilyl groups of the resulting ferrocene 3. Analysis of the deuterium content of the acetylferrocene 5 and the 1,1′-diacetylferrocene 7, obtained from the Friedel-Crafts acetylation of 4, reveals that the former is formed by initial exo attack of AlCl3-CH3COCl, whereas precomplexation of the electrophile at the metal center (endo attack) precedes the formation of the latter.
Cunningham Jr., Allan F.
p. 2480 - 2485
(1994)
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Dicationic Thiolate-Bridged Diruthenium Complexes for Catalytic Oxidation of Molecular Dihydrogen
Dicationic thiolate-bridged diruthenium complexes bearing sterically bulky alkane substituents on the thiolate ligands such as [Cp?Ru(μ-SiPr)2Ru(OH2)Cp?](OTf)2 have been found to work as effective catalysts toward oxidation of molecular dihydrogen into protons and electrons in protic solvents such as water and methanol. DFT calculations indicate that the sterically bulky alkane substituent in the complex plays an important role in facilitating the reaction step of the coordination of molecular dihydrogen.
Yuki, Masahiro,Sakata, Ken,Nakajima, Kazunari,Kikuchi, Syoma,Sekine, Shinobu,Kawai, Hiroyuki,Nishibayashi, Yoshiaki
p. 4499 - 4506
(2017)
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Oxidation of Ascorbic Acid by Copper(II) and the Ferrocenium Ion in Acetonitrile-Water Mixtures
Measurements are reported on the rates of oxidation of ascorbic acid (H2A) by copper(II) and the ferrocenium cation + in mixtures of water and acetonitrile.The stabilisation of Cu+ by acetonitrile results in a rapid increase in E0 for Cu2+ - Cu+ and simple, irreversible reaction between copper(II) and ascorbic acid to form copper(I) and dehydroascorbic acid upon addition of small amounts of acetonitrile to water.The acid dependence of the rate constant is consistent with the involvement of complexes of the monoanion, II(HA)>+, and the dianion IIA>, the former becoming relatively more important with increasing acetonitrile content of the solvent.The solvent dependence of the rate constant is discussed in relation to the solvation of copper(II) and copper(I) in the mixtures and it is suggested that the dominant influence is the solvation of copper(I) formed in the initial electron-transfer process.Redox potentials, E for + - , and rates of oxidation of ascorbic acid by ferrocenium, a typical outer-sphere oxidant, have been measured under the same conditions and are compared with those of the copper(II) - copper(I) system.
Cox, Brian G.,Jedral, Wojciech,Palou, Josefina
p. 733 - 740
(1988)
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Sandwich complexes of iron and ruthenium with the semiconducting aromatic hydrocarbon picene
Pentacyclic aromatic hydrocarbon picene C22H14 was synthesized by the improved two-step procedure from 1-naphthaldehyde in ca. 50% total yield. Reaction of picene with ferrocene in the presence of AlCl3 produced the binucl
Shved, Andrei M.,Nelyubina, Yulia V.,Perekalin, Dmitry S.
p. 24 - 28
(2018)
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Catalytic Activity of Thiolate-Bridged Diruthenium Complexes Bearing Pendent Ether Moieties in the Oxidation of Molecular Dihydrogen
Thiolate-bridged diruthenium complexes bearing pendent ethers have been found to work as effective catalysts toward the oxidation of molecular dihydrogen into protons and electrons in water. The pendent ether moiety in the complex plays an important role to facilitate the proton transfer between the metal center and the external proton acceptor.
Yuki, Masahiro,Sakata, Ken,Kikuchi, Shoma,Kawai, Hiroyuki,Takahashi, Tsuyoshi,Ando, Masaki,Nakajima, Kazunari,Nishibayashi, Yoshiaki
p. 1007 - 1012
(2017)
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Naphthocage: A Flexible yet Extremely Strong Binder for Singly Charged Organic Cations
We report a quite flexible naphthol-based cage (so-called "naphthocage") which adopts a self-inclusion conformation in its free state and is able to bind singly charged organic cations extremely strongly (Ka > 107 M-1). Ion-selective electrodes prepared with this naphthocage show a super-Nernstian response to acetylcholine. In addition, the highly stable complex (1010 M-1) between ferrocenium and the naphthocage can be switched electrochemically, which lays a basis for its application in stimuli-responsive materials.
Jia, Fei,Hupatz, Henrik,Schr?der, Hendrik V.,Witte, Felix,Paulus, Beate,Schalley, Christoph A.,Yang, Liu-Pan,Li, Dong-Hao,Xin, Shan,Xie, Xiaojiang,Jiang, Wei,Lentz, Dieter
p. 4468 - 4473
(2019)
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Ferra- and ruthenatricarbollides CpFeC3B8H 11 and Cp*RuC3B8H11
The room-temperature photochemical reaction of the tricarbollide anion [nido-7,8,9-C3B8H11]- (1a) with [CpFe(C6H6)]+ proceeds without cluster rearrangement to form the 12-vertex closo-ferratricarbollide 1-Cp-1,2,3,4-FeC3B8H11 (2a, the metal atom is assigned number 1). 2a rearranges to the isomeric complex 1-Cp-1,2,3,5-FeC 3B8H11 (2b) at 110°C and further to 1-Cp-1,2,4,10-FeC3B8H11 (2c) at 165°C. The reaction of la with [Cp*RuCl]4 is accompanied by polyhedral rearrangement giving 1-Cp*-1,2,3,5-RuC3B8H 11 (3b). Its further isomerization occurs slowly at room temperature and rapidly at 65°C to give complex 1-Cp*-1,2,4,10-RuC 3B8H11 (3c). Similar reactions of [nido-7,8,10-C3B8H11]- (1b) with [CpFe(C 6H6)]+ and [Cp*RuCl]4 afford 2b and 3b, respectively. A diamond-square-diamond mechanism for the 2a → 2b → 2c rearrangement sequence is proposed. The relative stability of isomers 2a-c was estimated by DFT calculations. The constitution of the compounds prepared was determined by multinuclear NMR spectroscopy and mass spectrometry. The structures of 2a, 2b, and 3c were established by X-ray diffraction.
Perekalin, Dmitry S.,Holub, Josef,Golovanov, Denis G.,Lyssenko, Konstantin A.,Petrovskii, Pavel V.,Stibr, Bohumil,Kudinov, Alexander R.
p. 4387 - 4392
(2005)
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A Study of the reaction of iron dichloride with the pyridine activated cyclopentadiene in anhydrous 2-propanol
A reaction was studied between iron dichloride solvate and pyridine activated cyclopentadiene in anhydrous 2-propanol. We showed that pyridine hydrochloride formed in the course of this reaction can be easily separated from the target product (ferrocene) and recycled after neutralization with sodium isopropoxide, which imparts the preparative value to the studied reaction.
Kurbanov
p. 1765 - 1767
(2011)
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SYNTHETIC AND STRUCTURAL STUDIES ON SOME 1,3-DISELENA-FERROCENOPHANES OF CARBON, SILICON AND TIN. CRYSTAL AND MOLECULAR STRUCTURE OF BIS(FERROCENE-1,1'-DISELENATO)TIN(IV) AT 163 K
A series of 1,3-diselena-ferrocenophanes of general formula Fe(C5H4Se)2Y, (Y=CH2, C(C6H5)2, Si(CH3)2, Si(C6H5)CH3, Sn(CH3)2 or Sn(C6H5)2) and a spiro compound 2Sn have been prepared by reaction of ferrocene-1,1'-diselenol and halide complexes of the Group IV elements.Spectroscopic properties of the compounds are reported.In solution these compounds are fluxional by a bridge-reversal process.The crystal structure of bis(ferrocene-1,1'-diselenato)tin(IV) has been determined at 163 K.At that temperature crystals have space group Pbcn with a 7.515(3), b 11.159(5) and c 24.308(10) Angstroem.Least-squares refinement gave R=0.040 for 2357 unique reflections whose intensities were measured by counter diffractometry.The molecules have two-fold crystallographic symmetry (Z=4) with the axis passing through the Sn atom.The Sn-Se bond lengths are 2.516(1) and 2.539(1) Angstroem, and the Se-Sn-Se valence angles show considerable variation, that in the ferrocenophane moiety being 108.6(1), and the others 104.5(2), 108.5(1), and 117.4(2) deg.The Se-C bond lengths are 1.901(4) and 1.903(4) Angstroem, with C-Se-Sn angles of 98.6(1) and 99.7(1) deg.The cyclopentadienyl rings are in an eclipsed conformation with a mean twist angle of 5.7 deg, and the Se atoms are displaced from the ring planes by 0.24 and 0.27 Angstroem yielding a non-bonded Se...Se separation of 4.00 Angstroem in the ferrocenophane moiety.
Osborne, A. G.,Hollands, R. E.,Bryan, R. F.,Lockhart, S.
p. 129 - 142
(1982)
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Redox-active complexes containing group 8 metal centers linked by C 2 bridges
A series of complexes containing dicarbon ligands bridging redox-active group 8 metal-ligand fragments M(dppe)Cp′ (M = Fe, Ru, Os; Cp′ = Cp, Cp*) have been prepared. These complexes give up to four one-electron anodic processes at a platinum electrode, with separations of successive oxidation potentials of ca. 850 mV, giving rise to large comproportionation constants, Kc (ca. 1012). Examples of the 36-electron neutral, 35-electron monocationic, and 34-electron dicationic species, together with some related monoprotonated complexes, have been isolated. Structural studies of the 36-, 35-, and 34-electron species derived from the dicarbon complex featuring two Ru(dppe)Cp end-caps (7) show that shortening of the M - C and lengthening of the C - C bonds occur upon oxidation. A complementary spectroelectrochemical investigation has revealed an intense band near 14 300 cm-1 associated with [7]PF6, which is tentatively attributed to a Ru(d) - [Ru(d)/C2(π)]* transition, rather than a genuine IVCT band. These observations have been rationalized using DFT calculations and collectively indicate that the frontier orbitais are delocalized over both group 8 metal centers and the carbon chain.
Bruce, Michael I.,Costuas, Karine,Ellis, Ben G.,Halet, Jean-Francois,Low, Paul J.,Moubaraki, Boujemaa,Murray, Keith S.,Ouddai, Nadia,Perkins, Gary J.,Skelton, Brian W.,White, Allan H.
p. 3735 - 3745
(2007)
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Photoresist based on metallocene compound and preparation method and application thereof
The invention belongs to the technical field of photoresist, and particularly relates to a photoresist based on a metallocene compound as well as a preparation method and application of the photoresist. The metallocene compound disclosed by the invention adopts metal as a central core structure, so that the metallocene compound has a relatively high melting point and glass-transition temperature, can meet the requirements of a photoetching technology, and is stable in structure, and a film structure is not changed during high-temperature baking. In addition, the photoresist composition provided by the invention can be used in modern photoetching processes such as 248nm photoetching, 193nm photoetching, extreme ultraviolet (EUV) photoetching, nanoimprint lithography (NIL), electron beam lithography (EBL) and the like, and is particularly suitable for being used in an extreme ultraviolet (EUV) photoetching process.
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(2021/05/26)

Reactions of Ferrocenium Hexafluorophosphate with P?OR Nucleophiles Give Ring C?H Functionalization or Ring Replacement Products Depending on the Phosphorus Reagent
Ferrocenium hexafluorophosphate reacts with different P?OR nucleophiles (PR3) in CH2Cl2 at room temperature to give either half-sandwich complexes [CpFe(PR3)3](PF6) (PR3=P(OMe)3, P(OEt)3, PhP(OMe)2) or ferrocenylphosphonium salts [CpFe(C5H4PR3)](PF6) (PR3=iPr2P(OMe), iPr2P(OEt)). Mixtures of both products are formed for some other nucleophiles (PR3=Ph2P(OMe), Ph2P(OEt), PhP(OiPr)2). The mechanism of the former reaction was established using DFT calculations. This reaction pathway is especially characteristic of π-acceptor nucleophiles, which is presumably explained by their ability to stabilize the 19e intermediates. The result of the reaction with tertiary phosphines, aminophosphines, and P?OR nucleophiles can be reliably predicted based on the values of the Tolman electronic parameter (below 2070 cm?1 – only ferrocenylphosphonium salt, in between 2073 cm?1 and 2080 cm?1 – only half-sandwich complex, and in the range from 2070 cm?1 to 2073 cm?1 – mixtures of both products).
Chamkin, Aleksandr A.,Krivykh, Vasily V.,Kreindlin, Arkady Z.,Dolgushin, Fedor M.,Ustynyuk, Nikolai A.
supporting information
p. 1601 - 1610
(2021/04/16)

A Mononuclear Non-heme Iron(III)-Peroxo Complex with an Unprecedented High O-O Stretch and Electrophilic Reactivity
A mononuclear non-heme iron(III)-peroxo complex, [Fe(III)(O2)(13-TMC)]+ (1), was synthesized and characterized spectroscopically; the characterization with electron paramagnetic resonance, M?ssbauer, X-ray absorption, and resonance Raman spectroscopies and mass spectrometry supported a high-spin S = 5/2 Fe(III) species binding an O2 unit. A notable observation was an unusually high νO-O at ～1000 cm-1 for the peroxo ligand. With regard to reactivity, 1 showed electrophilic reactivity in H atom abstraction (HAA) and O atom transfer (OAT) reactions. In the HAT reaction, a kinetic isotope effect (KIE) value of 5.8 was obtained in the oxidation of 9,10-dihydroanthracene. In the OAT reaction, a negative ρ value of -0.61 in the Hammett plot was determined in the oxidation of p-X-substituted thioanisoles. Another interesting observation was the electrophilic reactivity of 1 in the oxidation of benzaldehyde derivatives, such as a negative ρ value of -0.77 in the Hammett plot and a KIE value of 2.2. To the best of our knowledge, the present study reports the first example of a mononuclear non-heme iron(III)-peroxo complex with an unusually high νO-O value and unprecedented electrophilic reactivity in oxidation reactions.
Ezhov, Roman,Guo, Yisong,Jang, Semin,Kim, Taeyeon,Lee, Yong-Min,Li, Xiao-Xi,Nam, Wonwoo,Pushkar, Yulia,Sarangi, Ritimukta,Seo, Mi Sook,Xiong, Jin,Zhu, Wenjuan
supporting information
p. 15556 - 15561
(2021/10/01)

Iodoferrocene as a partner inN-arylation of amides
In this study, we developed a convenient methodology for theN-arylation of various acetamides, benzamides and related compounds by iodoferrocene. Optimization of the reaction was first performed from acetamide on the basis of the achievements in the benzene series. Next, the identified conditions (use of copper(i) iodide,N,N′-dimethylethylenediamine, tripotassium phosphate in dioxane at 90 °C for 14 h) were applied to different aliphatic/aromatic primary and cyclic/acyclic secondary amides in order to determine the scope of the reaction, thus easily generating a small library of ferrocene amides.
Kadari, Lingaswamy,Erb, William,Roisnel, Thierry,Radha Krishna, Palakodety,Mongin, Florence
p. 15928 - 15941
(2020/10/08)

Imidazolium Cyclopentadienide Salts and their Use as Cp-Transfer Reagents
The reaction of N-heterocyclic carbenes, 1a–c, towards cyclopentadienes, 2a–c, was studied. N,N′-diisopropyl-substituted carbene 1a acts as a Br?nsted base and deprotonates cyclopentadiene, 2a, and isopropylcyclopentadiene, 2b, to yield the corresponding imidazolium cyclopentadienide salts, 3a,b, whereas there is no reaction towards 1,2,3,4,5-pentamethylcyclopentadiene. Imidazolium cyclopentadienide salts, 3a,b, were characterized in solution by 1H and 13C NMR spectroscopy, as well as in the solid state by single-crystal X-ray diffraction. In addition, it was demonstrated that imidazolium cyclopentadienide salt 3a can be used as a Cp-transfer reagent in the synthesis of different cyclopentadienyl transition metal complexes.
Bischoff, Inga-Alexandra,Müller, Carsten,Huch, Volker,Zimmer, Michael,Sch?fer, André
p. 1941 - 1944
(2019/04/03)

Effect of ring size on the properties of μ3-Cycloalkyne complexes: Synthesis of triruthenium complexes containing a perpendicularly coordinated μ3-Allenyl ligand
A series of triruthenium complexes, [{Cp*Ru(μ-H)}3(μ3-η2:η2-CnH2n-4)] (2a, n = 6; 2b, n = 7; 2c, n = 8), containing a triply bridgin cycloalkyne ligand was synthesized. Although no noticeable differences were detected in the ground state, the rate of dynamic motion of the cycloalkyne ligand increased remarkably as the ring size increased. Owing to the flexibility of the larger rings, an allylic C–H bond can interact with one of the metal centers, stabilizing the transition state of the dynamic process. This interaction also caused allylic C–H bond scission upon chemical oxidation. In the case of 2b and 2c, a cationic μ3-η2:η2:η2-allenyl complex, [{Cp*Ru(μ-H)}3(μ3-η2:η2:η2-CnH2n-5)]+ (3b, n = 7; 3c, n = 8), was obtained. X-ray diffraction studies of 3 clearly show that the allenyl group is coordinated to one of the Ru-Ru bonds in a perpendicular fashion, unlike the known “parallel” μ3-allenyl complexes. In contrast to the reactions of 2b and 2c, chemical oxidation of 2a occurred via the incorporation of adventitious H2O rather than intramolecular C-H bond cleavage. Consequently, cationic μ3-cyclohexyne-μ-hydroxo complex, [{Cp*Ru(μ-H)}3(μ-OH)(μ3-η2-C6H8)]+ (5a) was obtained in 38% yield by the reaction with 2 equiv [Cp2Fe]+ in the presence of excess water. These results clearly show that the reaction pathway of the μ3-cycloalkyne complex varies with the ring size.
Saito, Moeko,Kojima, Shuhei,Inagaki, Akiko,Seki, Koichi,Takao, Toshiro
p. 7 - 20
(2019/02/19)

Reaction of ferrocenium ion with secondary phosphines: replacement of cyclopentadienyl ligand rather than its C—H functionalization
The reactions of ferrocenium salts with secondary phosphines Ph2PH, Cy2PH, and Et2PH proceed as replacement of the cyclopentadienyl ring to afford half-sandwich complexes [C5H5Fe(R2PH)3](X) (X = PF6, BF4) rather than ferrocenylphosphonium salts [C5H5FeC5H4— (PHR2)](X).
Chamkin,Krivykh,Shtel′tser,Utegenov,Dolgushin,Ustynyuk
p. 1380 - 1383
(2019/08/12)

Oxidation of Iron Complex with NHC Ligand with Molecular Iodine
Abstract: Complex (η5-C5H5)2Fe2(CO)4 (I) reacts with 1,3-dimethylimidazolium-2-carboxylate Me2ImCO2 to give asymmetric binuclear carbene iron complex (η5-C5H5)2Fe2(CO)3(Me2Im) (II) (Me2Im = 1,3-dimethylimidazol-2-ylidene). The oxidation of compound II with elemental iodine proceeds via two mechanisms, symmetrical and asymmetrical, to form four products: (η5-C5H5Fe(CO)2(Me2Im)I (III), (η5-C5H5)Fe(CO)2I (IV), (η5-C5H5Fe(CO)2(Me2Im)I3 (V), and ferrocene (VI). In each case, two pairs of reaction products have formed, two of which include NHC ligand: neutral iron(III) complex and ionic complex V. Optimal synthesis conditions to obtain preferably one of these complexes have been found. Geometry and transition state energy of supposed reaction mechanism have been calculated by quantum chemistry methods.
Shapovalov,Tikhonova,Skabitskii,Kolos,Sakharov,Torubaev, Yu. V.
p. 1418 - 1423
(2019/12/25)

Frustrated Lewis pairs incorporating the bifunctional Lewis acid 1,1′-fc{B(C6F5)2}2: Reactivity towards small molecules
Applications of the bifunctional ferrocenediyl Lewis acid 1,1′-fc{B(C6F5)2}2 in frustrated Lewis pair (FLP) chemistry are described. The coordination (or otherwise) of a range of sterically encumbered C-, N- and P-centred Lewis bases has been investigated, with lutidine, tetramethylpiperidine, PPh3, PtBu3 and the expanded ring carbene 6Dipp being found to be sterically incapable of coordinate bond formation. The chemistry of a range of these FLPs in the presence of H2O, NH3, CO2 and cyclohexylisocyanate (CyNCO) has been investigated, with the patterns of reactivity identified including simple coordination chemistry, E-H bond cleavage and C-B insertion.
Tirfoin, Rémi,Gilbert, Jessica,Kelly, Michael J.,Aldridge, Simon
p. 1588 - 1598
(2018/02/09)

Functional Synthetic Model for the Lanthanide-Dependent Quinoid Alcohol Dehydrogenase Active Site
The oxidation of methanol by dehydrogenase enzymes is an essential part of the bacterial methane metabolism cycle. The recent discovery of a lanthanide (Ln) cation in the active site of the XoxF dehydrogenase represents the only example of a rare-earth element in a physiological role. Herein, we report the first synthetic, functional model of Ln-dependent dehydrogenase and its stoichiometric and catalytic dehydrogenation of a benzyl alcohol. Density functional theory calculations implicate a hydride transfer mechanism for these reactions.
McSkimming, Alex,Cheisson, Thibault,Carroll, Patrick J.,Schelter, Eric J.
supporting information
p. 1223 - 1226
(2018/02/09)

Synthesis and reactivity of a water-soluble NiRu monohydride complex with a tethered pyridine moiety
We report the synthesis, characterization, and reactivity of a NiRu monohydride complex with a pyridine-bound hexamethylbenzene ligand. We investigate the mechanistic insights it provides on the H2-activation of [NiFe]hydrogenase.
Matsumoto, Takahiro,Yoshimoto, Koji,Zheng, Chunbai,Shomura, Yasuhito,Higuchi, Yoshiki,Nakai, Hidetaka,Ogo, Seiji
supporting information
p. 197 - 199
(2016/03/01)

Oxidatively Triggered Carbon-Carbon Bond Formation in Ene-amide Complexes
Ene-amides have been explored as ligands and substrates for oxidative coupling. Treatment of CrCl2, Cl2Fe(PMe3)2, and Cl2Copy4 with 2 equiv of {(2,6-iPr2C6H3)(1-cHexenyl)N}Li afforded pseudosquare planar {3-C,C,N-(2,6-iPr2C6H3)(1-cHexenyl)N}2Cr (1-Cr, 78%), trigonal {(2,6-iPr2C6H3)(1-cHexenyl)N}2Fe(PMe3) (2-Fe, 80%), and tetrahedral {(2,6-iPr2C6H3)(1-cHexenyl)N}2Co(py)2 (3-Co, 91%) in very good yields. The addition of CrCl3 to 1-Cr, and FeCl3 to 2-Fe, afforded oxidatively triggered C-C bond formation as rac-2,2′-di(2,6-iPr2C6H3N - )2dicyclohexane (EA2) was produced in modest yields. Various lithium ene-amides were similarly coupled, and the mechanism was assessed via stoichiometric reactions. Some ferrous compounds (e.g., 2-Fe, FeCl2) were shown to catalyze C-arylation of {(2,6-iPr2C6H3)(1-cHexenyl)N}Li with PhBr, but the reaction was variable. Structural characterizations of 1-Cr, 2-Fe, and 3-Co are reported.
Jacobs, Brian P.,Wolczanski, Peter T.,Lobkovsky, Emil B.
supporting information
p. 4223 - 4232
(2016/05/24)

HYDROGEN OXIDATION CATALYST
The present invention is to provide a hydrogen oxidation catalyst that does not contain platinum. Disclosed is a hydrogen oxidation catalyst that is a dinuclear transition metal complex having a chemical structure represented by the following general formula (1) or (2): wherein, in the general formulae (1) and (2), M1 and M2 are each independently Fe or Ru; Ar1 and Ar2 are each independently a cyclopentadienyl group or a pentamethylcyclopentadienyl group; Ar3 and Ar4 are each independently a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms; and Ar5 is a monovalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and in the general formula (2), R1 and R2 are each independently a hydrogen atom or a monovalent aliphatic hydrocarbon group having 1 to 3 carbon atoms.
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(2017/01/09)

Thiolate-bridged dinuclear ruthenium and iron complexes as robust and efficient catalysts toward oxidation of molecular dihydrogen in protic solvents
Thiolate-bridged dinuclear ruthenium and iron complexes are found to work as efficient catalysts toward oxidation of molecular dihydrogen in protic solvents such as water and methanol under ambient reaction conditions. Heterolytic cleavage of the coordinated molecular dihydrogen at the dinuclear complexes and the sequential oxidation of the produced hydride complexes are involved as key steps to promote the present catalytic reaction. The catalytic activity of the dinuclear complexes toward the chemical oxidation of molecular dihydrogen achieves up to 10000 TON (turnover number), and electrooxidation of molecular dihydrogen proceeds quite rapidly. The result of the density functional theory (DFT) calculation on the reaction pathway indicates that a synergistic effect between the two ruthenium atoms plays an important role to realize the catalytic oxidation of molecular dihydrogen efficiently. The present dinuclear ruthenium complex is found to work as an efficient organometallic anode catalyst for the fuel cell. It is noteworthy that the present dinuclear complex worked not only as an effective catalyst toward chemical and electrochemical oxidation of molecular dihydrogen but also as a good anode catalyst for the fuel cell. We consider that the result described in this paper provides useful and valuable information to develop highly efficient and low-cost transition metal complexes as anode catalysts in the fuel cell.
Yuki, Masahiro,Sakata, Ken,Hirao, Yoshifumi,Nonoyama, Nobuaki,Nakajima, Kazunari,Nishibayashi, Yoshiaki
supporting information
p. 4173 - 4182
(2015/04/14)

The titanium tris-anilide cation [Ti(N[tBu]Ar)3]+ stabilized as its perfluoro-tetra-phenylborate salt: Structural characterization and synthesis in connection with redox activity of 4,4′-bipyridine dititanium complexes
This work explores the reduction of 4,4′-bipyridine using two equivalents of the titanium(iii) complex Ti(N[tBu]Ar)3 resulting in formation of a black, crystalline complex, (4,4′-bipy){Ti(N[tBu]Ar)3}2, for which an X-ray structure determination is reported. The neutral, black, 4,4′-bipyridine-bridged bimetallic was found to be redox active, with mono- and di-anions being accessible electrochemically, and with the mono- and di-cations also being accessible chemically, and isolable, at least when using the weakly coordinating anion [B(C6F5)4]- as the counter-ion. It proved possible to crystallize the salt [(4,4′-bipy){Ti(N[tBu]Ar)3}2][B(C6F5)4]2 for a single-crystal X-ray structure investigation; in this instance it was revealed that the aromaticity of the 4,4′-bipyridine ligand, that had been disrupted upon reduction, had been regained. A rare cationic d0 metal tris-amide complex, shown by X-ray crystallography to contain an intriguing pyramidal TiN3 core geometry, namely {Ti(N[tBu]Ar)3}+, could also be isolated when using [B(C6F5)4] as the essentially non-interacting counter-ion. This highly reactive cation should be considered as a potential intermediate in the plethora of reactions wherein Ti(N[tBu]Ar)3 has been shown to effect the reduction of substrates including halogenated organic molecules, carbonyl compounds, organic nitriles, and metal complexes. This journal is
Spinney, Heather A.,Clough, Christopher R.,Cummins, Christopher C.
p. 6784 - 6796
(2015/04/14)

Halide-Mediated Ortho-Deprotonation Reactions Applied to the Synthesis of 1,2- and 1,3-Disubstituted Ferrocene Derivatives
The ortho-deprotonation of halide-substituted ferrocenes by treatment with lithium tetramethylpiperidide (LiTMP) has been investigated. Iodo-, bromo-, and chloro-substituted ferrocenes were easily deprotonated adjacent to the halide substituents. The synthetic applicability of this reaction was, however, limited by the fact that, depending on the temperature and the degree of halide substitution, scrambling of both iodo and bromo substituents at the ferrocene core took place. Iodoferrocenes could not be transformed selectively into ortho-substituted iodoferrocenes since, in the presence of LiTMP, the iodo substituents scrambled efficiently even at -78°C, and this process had occurred before electrophiles had been added. Bromoferrocene and certain monobromo-substituted derivatives, however, could be efficiently ortho-deprotonated at low temperature and reacted with a number of electrophiles to afford 1,2- and 1,2,3-substituted ferrocene derivatives. For example, 2-bromo-1-iodoferrocene was synthesized by ortho-deprotonation of bromoferrocene and reaction with the electrophiles diiodoethane and diiodotetrafluoroethane, respectively. In this and related cases the iodide scrambling process and further product deprotonation due to the excess LiTMP could be suppressed efficiently by running the reaction at low temperature and in inverse mode. In contrast to the low-temperature process, at room temperature bromo substituents in bromoferrocenes scrambled in the presence of LiTMP. Chloro- and 1,2-dichloroferrocene could be ortho-deprotonated selectively, but in neither case was scrambling of a chloro substituent observed. As a further application of this ortho-deprotonation reaction, a route for the synthesis of 1,3-disubstituted ferrocenes was developed. 1,3-Diiodoferrocene was accessible from bromoferrocene in four steps. On a multigram scale an overall yield of 41% was achieved. 1,3-Diiodoferrocene was further transformed into symmetrically 1,3-disubstituted ferrocenes (1,3-R2Fc; R = CHO, COOEt, CN, CH = CH2). (Figure Presented).
Zirakzadeh, Afrooz,Herlein, Alexander,Gross, Manuela A.,Mereiter, Kurt,Wang, Yaping,Weissensteiner, Walter
p. 3820 - 3832
(2015/08/24)

Experimental and Computational Characterization of the Transition State for C-X Bimetallic Oxidative Addition at a Cu-Fe Reaction Center
The heterobimetallic complex (IPr)Cu-Fp (IPr = N,N′-bis(2,6-diisopropylimidazol-2-ylidene, Fp = FeCp(CO)2) was identified previously as a nonprecious metal catalyst for C-H borylation. To better understand the nature of the bimetallic reaction pathways operative in this system, we have conducted a thorough mechanistic study of alkyl halide activation by the Cu-Fe heterobimetallic reaction center. Use of cyclopropylmethyl halide substrates as radical clocks established that alkyl halide activation occurs by a two-electron mechanism for alkyl bromides and chlorides but not iodides. Eyring analysis of the activation of benzyl chloride allowed for experimental determination of activation parameters, including a large and negative entropy of activation (ΔS? = -36 eu). A Hammett study with para-substituted benzyl chlorides revealed a reaction constant of ρ = 1.6, indicating accumulation of negative charge in the transition state on the alkyl halide carbon. The Ru analogue, (IPr)Cu-Rp (Rp = RuCp(CO)2), was found to react approximately 17-25 times more slowly with selected benzyl chlorides than (IPr)Cu-Fp, indicating that the relative nucleophilicities of the free metal carbonyl anions are predictive of the relative reactivities of their heterobimetallic counterparts. Synthesis and characterization of the new Ag and Au analogues, (IPr)Ag-Fp and (IPr)Au-Fp, are reported along with the observation that these more covalent congeners are significantly less reactive toward alkyl halides. DFT calculations were used to model a transition state for the Cu-Fe reaction, which was identified as stereoinvertive at the alkyl halide carbon. NBO calculations indicate crucial roles played by the CO ligands within the Fp group: they both act as redox noninnocent ligands and also provide structural templating to stabilize the transition state as the metal-metal bond breaks. (Chemical Equation Presented).
Karunananda, Malkanthi K.,Parmelee, Sean R.,Waldhart, Greyson W.,Mankad, Neal P.
p. 3857 - 3864
(2015/08/19)

Organometallic nickel(III) complexes relevant to cross-coupling and carbon-heteroatom bond formation reactions
Nickel complexes have been widely employed as catalysts in C-C and C-heteroatom bond formation reactions. In addition to Ni(0) and Ni(II) intermediates, several Ni-catalyzed reactions are proposed to also involve odd-electron Ni(I) and Ni(III) oxidation states. We report herein the isolation, structural and spectroscopic characterization, and organometallic reactivity of Ni(III) complexes containing aryl and alkyl ligands. These Ni(III) species undergo transmetalation and/or reductive elimination reactions to form new C-C or C-heteroatom bonds and are also competent catalysts for Kumada and Negishi cross-coupling reactions. Overall, these results provide strong evidence for the direct involvement of organometallic Ni(III) species in cross-coupling reactions and oxidatively induced C-heteroatom bond formation reactions.
Zheng, Bo,Tang, Fengzhi,Luo, Jia,Schultz, Jason W.,Rath, Nigam P.,Mirica, Liviu M.
supporting information
p. 6499 - 6504
(2014/05/20)

A heterobimetallic approach to stabilize the elusive disulfur radical trianion ( subsulfide ) S23-
A unique heterobimetallic disulfur monoradical, complex 2, with a diamond-shaped {NiS2Pt} core has been synthesized by two-electron reduction of a supersulfido-(nacnac)nickel(II) complex (nacnac=β- diketiminato) with [Pt(Ph3P)2(η2-C 2H4)] as a platinum(0) source and isolated in 82 % yield. Strikingly, the results of DFT calculations in accordance with spectroscopic (EPR, paramagnetic NMR) and structural features of the complex revealed that the bonding situation of the S2 ligand is between the elusive half-bonded S2 radical trianion (S2 3-) and two separated S2- ligands. Accordingly, the NiII center is partially oxidized, whereas the PtII site is redox innocent. The complex can be reversibly oxidized to the corresponding Ni,Pt-disulfido monocation, compound 3, with a S-S single bond, and reacts readily with O2 to form the corresponding superoxonickel(II) and disulfidoplatinum(II) (4) complexes. These compounds have been isolated in crystalline form and fully characterized, including IR and multi-nuclear NMR spectroscopy as well as ESI mass spectrometry. The molecular structures of compounds 2-4 have been confirmed by single-crystal X-ray crystallography. Copyright
Yao, Shenglai,Hrobarik, Peter,Meier, Florian,Rudolph, Robert,Bill, Eckhard,Irran, Elisabeth,Kaupp, Martin,Driess, Matthias
p. 1246 - 1253
(2013/03/14)

Insight into one-electron oxidation of the {Fe(NO)2}9 dinitrosyl iron complex (DNIC): Aminyl radical stabilized by [Fe(NO) 2] motif
A reversible redox reaction ({Fe(NO)2}9 DNIC [(NO)2Fe(N(Mes)(TMS))2]- (4) ? oxidized-form DNIC [(NO)2Fe(N(Mes)(TMS))2] (5) (Mes = mesityl, TMS = trimethylsilane)), characterized by IR, UV-vis, 1H/15N NMR, SQUID, XAS, single-crystal X-ray structure, and DFT calculation, was demonstrated. The electronic structure of the oxidized-form DNIC 5 (Stotal = 0) may be best described as the delocalized aminyl radical [(N(Mes)(TMS))2]2 -? stabilized by the electron-deficient {Fe III(NO-)2}9 motif, that is, substantial spin is delocalized onto the [(N(Mes)(TMS))2] 2-? such that the highly covalent dinitrosyl iron core (DNIC) is preserved. In addition to IR, EPR (g ≈ 2.03 for {Fe(NO) 2}9), single-crystal X-ray structure (Fe-N(O) and N-O bond distances), and Fe K-edge pre-edge energy (7113.1-7113.3 eV for {Fe(NO) 2}10 vs 7113.4-7113.9 eV for {Fe(NO)2} 9), the 15N NMR spectrum of [Fe(15NO) 2] was also explored to serve as an efficient tool to characterize and discriminate {Fe(NO)2}9 (δ 23.1-76.1 ppm) and {Fe(NO)2}10 (δ -7.8-25.0 ppm) DNICs. To the best of our knowledge, DNIC 5 is the first structurally characterized tetrahedral DNIC formulated as covalent-delocalized [{FeIII(NO-) 2}9-[N(Mes)(TMS)]2-?]. This result may explain why all tetrahedral DNICs containing monodentate-coordinate ligands isolated and characterized nowadays are confined in the {Fe(NO) 2}9 and {Fe(NO)2}10 DNICs in chemistry and biology.
Tsou, Chih-Chin,Tsai, Fu-Te,Chen, Huang-Yeh,Hsu, I-Jui,Liaw, Wen-Feng
p. 1631 - 1639
(2013/04/10)

Dehydrogenation of alcohols by bis(phosphinite) benzene based and bis(phosphine) ruthenocene based iridium pincer complexes
Dehydrogenation of alcohols by three iridium pincer complexes, IrH(Cl)[2,6-(tBu2PO)2C6H 3] (1), {IrH(acetone)[2,6-(tBu2PO) 2C6H3]}{BF4} (2), and IrH(Cl)[{2,5-(tBu2PCH2)2C 5H2}Ru(C5H5)] (3), is reported, in both the presence and the absence of a sacrificial hydrogen acceptor. Dehydrogenation of secondary alcohols proceeds in a catalytic mode with turnover numbers up to 3420 (85% conversion) for acceptorless dehydrogenation of 1-phenylethanol. Primary alcohols are readily decarbonylated even at room temperature to give catalytically inactive 16e Ir-CO adducts. The mechanism of this transformation was studied in detail, especially for EtOH; new intermediates were isolated and characterized.
Polukeev, Alexey V.,Petrovskii, Pavel V.,Peregudov, Alexander S.,Ezernitskaya, Mariam G.,Koridze, Avthandil A.
p. 1000 - 1015
(2013/05/08)

Steric and electronic effects in the formation and carbon disulfide reactivity of dinuclear nickel complexes supported by bis(iminopyridine) ligands
We are developing bimetallic platforms for the cooperative activation of heteroallenes. Toward this goal, we designed a new family of bis(iminopyridine) ((N,N′-1,1′-(1,4-phenylene)bis(N-(pyridin-2-ylmethylene)methanamine) and N,N′-1,1′-(1,4-phenylene)bis(N-(1-(pyridin-2-yl)ethylidene) methanamine)) dinickel complexes, synthesized their CS2 compounds, and studied their reactivity. Bis(iminopyridine) ligands L react with Ni(COD)2 to form Ni2(L)2 complexes or Ni 2(L)(COD)2 complexes as a function of the steric and electronic properties of the ligand precursor. Product structures disclosed an anti geometry in the Ni2(L)(COD)2 species and helical (anti) structures for Ni2(L)2 complexes. Carbon disulfide adducts Ni2(L)(CS2)2 were obtained in good yields upon addition of CS2 to Ni2(L)(COD)2 or in a one-pot reaction of L with 2 equiv of both Ni(COD)2 and CS 2. Ni2(L)(CS2)2 complexes are highly flexible, displaying both syn and anti conformations (shortest S- - -S separations of 5.0 and 9.5 A, respectively) in the solid state. DFT calculations demonstrate virtually no energy difference between the two conformations. Electrochemical studies of the Ni2(L)(CS 2)2 complexes displayed two ligand-based reductions and a broad CS2-based oxidation. Chemical oxidation with [FeCp 2]+ liberated free CS2. The addition of NHC (NHC = 1,3-di-tert-butylimidazolin-2-ylidene) to Ni2(L)(CS 2)2 yielded Ni2(NHC)2(CS 2)2, in which both carbon disulfide ligands are bridging two Ni centers.
Bheemaraju, Amarnath,Beattie, Jeffrey W.,Tabasan, Erwyn G.,Martin, Philip D.,Lord, Richard L.,Groysman, Stanislav
p. 2952 - 2962
(2013/06/27)

Formal insertion of o-carborynes into ferrocenyl C-H bonds: A simple access to o-carboranylferrocenes
Insertion of o-carborynes (1,2-dehydro-o-carboranes) into ferrocenyl C-H bonds has been described, providing a convenient methodology for the preparation of functionalized ferrocenyl o-carboranes. Reaction of the carboryne precursors 1-I-2-Li-9,12-Me2-1,2-C2B10H8 or 1-I-2-Li-3-R-1,2-C2B10H9 (R = H, Ph, Me, Cl, Br, and I) with 2.5 equiv of ferrocene at 80 °C in cyclohexane afforded [1-(η5-C5H4)(9,12-Me2-1,2-C 2B10H9)]Fe(η5-C 5H5) and [1-(η5-C5H 4)(3-R-1,2-C2B10H10)] Fe(η5-C5H5) (R = H, Ph, Me, Cl, Br, and I) in 19-44% isolated yields. On the other hand, in addition to the desired C-H bond insertion products [1-(η5-C5H4)(3-X-1, 2-C2B10H10)]Fe(η5-C 5H5), bis(ferrocenyl)-o-carboranes 1,2- [(η5-C5H5)Fe(η5-C 5H4)]2-3-X-1,2-C2B 10H9 were isolated from the reactions of 1-I-2-Li-3-X-1,2-C2B10H9 (X = Cl, Br, and I) in 12%, 15%, and 8% yields, respectively. Treatment of 1,2-dilithio-o-carborane or 1-lithio-2-methyl-o-carborane with ferrocenium hexafluorophosphate in cyclohexane also generated [1-(η5-C5H 4)(1,2-C2B10H11)] Fe(η5-C5H5) and [1-(η5- C5H4)(2-Me-1,2-C2B10H 10)]Fe(η5-C5H5) in 17% and 31% isolated yields, respectively. On the basis of these observations, it is suggested that the single-electron oxidation of ferrocene to the electrophilic ferrocenium cation by o-carborynes is crucial for the insertion reaction. Accordingly, a reaction mechanism is proposed.
Wang, Sunewang Rixin,Xie, Zuowei
p. 4544 - 4550
(2012/07/14)

Ferrocenes containing a pendant propargylic chain obtained via addition of propargyl alcohol to μ-vinyliminium ligands in diiron complexes
The diiron bridging vinyliminium complexes [Fe2{μ- η1:η3-C=N(Me)2C(R′)=C(R″)} (μ-CO)(CO)(Cp)2][SO3CF3] (R′ = H, R″ = SiMe3, 3a; R′ = H, R″ = Tol =4-MeC 6H4, 3b; R′ = Me, R″ = Me, 3c; R′ = SPh, R″ = Me, 3d; R′ = H, R″ = Fc = [Fe(C5H 4)(Cp)], 6e) react with propargyl alcohol (HC≡CCH 2OH), in refluxing toluene, affording the polysubstituted ferrocenes as mixtures of two isomeric forms: [1-NMe2-2-R′-3-R″-5- CH2OCH2C≡CH-Fc] (R′ = H, R″ = SiMe 3, 6a; R′ = H, R″ = Tol, 6b; R′ = Me, R″ = Me, 6c; R′ = SPh, R″ = Me, 6d, R′ = H, R″ = Fc, 6e) and [1-NMe2-2-R′-3-R″-4-CH2OCH2C≡ CH-Fc] (R′ = H, R″ = SiMe3, 7a; R′ = H, R″ = Tol, 7b; R′ = Me, R″ = Me, 7c; R′ = SPh, R″ = Me, 7d) in overall yields of about 55-65%. Formation of the functionalized cyclopentadienyl in the ferrocene products takes place through the assembly of two propargyl units with the bridging vinyliminium ligand: one alkynol is incorporated by a [3 + 2] cycloaddition with the bridging C3 ligand; a second alkynol unit gives rise to a pendant chain through -OH substitution. Investigations show that the substitution step is catalyzed by the parent diiron complex itself or by a mononuclear iron fragment (likely the Fp+ complex). The pendant propargyl chain has been exploited to connect the ferrocene to other molecular fragments: in particular, the reaction of 6a with 4-biphenyl azide, by copper-catalyzed azide-alkyne cycloaddition (CuAAC), leads to the formation of the triazole-functionalized ferrocene [1-NMe 2-2-CH2OCH2-N3(C6H 4Ph)C2H-4-SiMe3-Fc] (12). Moreover, 6a reacts with Co2(CO)8, affording the complex [Co 2{μ-η2-HC≡CR}(CO)6] (13), (HC≡CR = 6a), where the alkyne adopts a η2 coordination to a dicobalt hexacarbonyl fragment. The molecular structure of 7a has been determined by X-ray diffraction studies.
Busetto, Luigi,Mazzoni, Rita,Salmi, Mauro,Zacchini, Stefano,Zanotti, Valerio
p. 2667 - 2674
(2012/06/01)

Synthesis and decarbonylation reactions of diiron cyclopentadienyl complexes with bent-phosphinidene bridges
The phosphinidene complexes [Fe2Cp2(μ-PR)(μ-CO) (CO)2] (Cp = η5-C5H5; R=Cy, Ph, Mes, Mes* Mes = 2,4,6-C6H2Me3, Mes* = 2,4,6-C6H2tBu3) were readily prepared in high yields through a two-step procedure starting from the corresponding phosphine complexes [Fe2Cp2(μ-CO) 2(CO)(PH2R)]. When R = Cy, Ph, Mes, the first step required the oxidation of the phosphine complex with 1 equiv of [FeCp 2]BF4, this being followed by spontaneous dehydrogenation to yield the cationic phosphide complexes [Fe2Cp2(μ- PHR)(μ-CO)(CO)2]BF4, while the formation of the related PMes*H-bridged complex required a double oxidation of the corresponding neutral precursor in the presence of a deprotonating agent. In all cases the final step involved the deprotonation of the above cations with strong bases such as M(OH) (M = Na, K). Attempts to decarbonylate the above phosphinidene complexes by either thermolysis or photolysis in solution gave results strongly dependent on the nature of R. Thus, the photolysis of the cyclohexylphosphinidene complex gave a mixture of the clusters [Fe 4Cp4(μ3-PCy)2(μ3- CO)(μ-CO)(CO)] (Fe-Fe distances 2.6115(7) and 2.5332(8) A) and [Fe 3Cp3(μ3-PCy)(μ-PCyH)(μ-CO) 2], while the thermal decarbonylation of the mesitylphosphinidene complex in refluxing toluene gave the trinuclear derivative [Fe 3Cp3(μ-PMes)(μ-PMesH)(μ-CO)2(CO)], having a trigonal phosphinidene ligand bridging two iron atoms (Fe-P = 2.161(8), 2.165(8) A). The formation of all these compounds presumably involves the participation of the corresponding intermediate complex [Fe2Cp 2(μ-PR)(μ-CO)2], a species likely to contain a trigonal (four-electron-donor) phosphinidene ligand, not detected. In contrast, the supermesitylphosphinidene complex undergoes a C(tBu)-H oxidative addition to the P atom under mild thermal conditions to give the phosphine derivative [Fe2Cp2(μ-CO)2(CO){PH(CH 2CMe2)C6H2tBu 2}], while its photolysis gave a mixture of the above phosphine complex and the phosphide-hydride derivatives cis- and trans-[Fe 2Cp2(μ-H){μ-P(CH2CMe2)C 6H2tBu2}(CO)2], the latter resulting from the oxidative addition of a P-H bond to the dimetal center.
Alvarez, M. Angeles,Garcia, M. Esther,Gonzalez, Rocio,Ramos, Alberto,Ruiz, Miguel A.
p. 1102 - 1115
(2011/04/22)

Coordination chemistry of perhalogenated cyclopentadienes and alkynes. XXVIII [1] new high-yield synthesis of monobromoferrocene and simplified procedure for the synthesis of pentabromoferrocene. Molecular structures of1,2,3-tribromoferrocene and 1,2,3,4,5-pentabromoferrocene
Monobromoferrocene (1) was obtained in 95% yield from ferrocene via lithiation with tert-BuLi/KO-tert-Bu and bromination with dibromotetrachloroethane. Starting from 1 mixtures of 1,2-dibromoferrocene (2) and apparently unreacted 1 (ranging from 80:20 to 50:50, depending on the reaction conditions) can be obtained via a lithiation- zincation- bromination sequence. These mixtures can be transferred directly with a tenfold excess of Lithium-tetramethylpiperidinide, followed by bromination with 1,1,2,2-tetrabromoethane to pentabromoferrocene (3), in an overall yield of 36% starting from ferrocene. The molecular structures of 3 and of 1,2,3-tribromoferrocene (4) have been determined by X-Ray diffraction.
Sünkel, Karlheinz,Bernhartzeder, Stefanie
p. 1536 - 1540
(2011/05/11)

Reactions of ferricinium salts with Lewis bases
A reaction of the ferricinium radical cation with Lewis bases leads to substitution in the cyclopentadienyl ring with the formation of ferrocene derivatives only when the radicals are formed from the Lewis bases in the process of the reaction.
Babin,Belousov,Belousova,Borisov,Gumenyuk,Nekrasov
p. 2081 - 2087
(2012/08/29)

Oxidation of dihydrogen by iridium complexes of redox-active ligands
Unsaturated organoiridium complexes were prepared with amidophenolate ligands derived from 2-(2-trifluoromethyl)amino-4,6-di-tert-butylphenol (H 2tBAF) and 2-tert-butylamino-4,6-di-tert- butylphenol (H2tBAtBu). The following 16e complexes were characterized: Cp*M(tBAR) with M = Ir (1F and 1t-Bu), Rh (2F), and (cymene)Ru( tBAF) (3F). These complexes undergo two 1e oxidations at potentials of about 0 and -0.25 V vs Cp2Fe 0/+. The magnitude of δE1/2 is sensitive to the counteranions, and the reversibility is strongly affected by the presence of Lewis bases, which stabilize the oxidized derivatives. Crystallographic measurements indicate that upon oxidation the amidophenolate ligands adopt quinoid character, as indicated by increased alternation of the C-C bond lengths in the phenylene ring backbone and shortened C-N and C-O bonds. Unlike the charge-neutral precursors, the cationic [Cp*M(tBA R)]+ are Lewis acidic and form well-characterized adducts with PR3 (R = Me, Ph), CN-, MeCN (reversibly), and CO. In the absence of competing ligands, the cations oxidize H2. Coulommetry measurements indicate that H2 is oxidized by the monocations [Cp*M(tBAR)]+, not the corresponding dications. Oxidation of H2 is catalytic in the presence of a noncoordinating base at potentials required for the generation of [Cp*M(tBAR)]+. The rate decreases in the order [Cp*M(tBAF)]BArF4 > [Cp*M(tBAF)]PF6 > [Cp*M( tBAt-Bu)]PF6. The reduction of ferrocenium by H2 is catalyzed by Cp*M(tBAR).
Ringenberg, Mark R.,Nilges, Mark J.,Rauchfuss, Thomas B.,Wilson, Scott R.
p. 1956 - 1965
(2010/06/14)

[Cp*Ru(s-indacene)RuCp*] and [Cp*Ru(s-indacene)RuCp*]+: Experimental and theoretical findings concerning the electronic structure of neutral and mixed valence organometallic systems
The reaction of 2,6-diethyl-4,8-dimethyl-s-indacenyl-dilithium (Li2Ic′) with [Cp*RuCl]4 gives the organometallic binuclear bis-pentamethylcyclopentadienyl-ruthenium-s-indacene complex, [{Cp*Ru}2Ic′] (1, Ic′ = 2,4-diethyl-4,8-dimethyl-s-indacene), in high yields. The subsequent oxidation of 1 with a ferricinium salt ([Fc]+[BF4]-) gives the mixed valence compound [{Cp*Ru}2Ic′]+[BF4]- (1+). Compound 1 was structurally characterized by X-ray crystallography, finding that both {Cp*Ru} fragments are coordinated to opposite sites of the Ic′ ligand. The structural and electronic features of 1 and 1+ have been rationalized by Density Functional Theory (DFT) calculations, which suggest that both metallic centers get closer to the Ic′ and subtle electronic reorganizations occurs when chemical oxidation takes place. Cyclic voltammetry and ESR experiments suggest a high electronic interaction between the metallic centers mediated by the Ic′ bridging ligand. Time dependent DFT (TD-DFT) calculations were carried out to understand and assign the intervalence band present in the mixed-valent specie (1+). The main achievement of this article is to feature the relationship of the experimental data with the computational results obtained with the Amsterdam Density Functional package (ADF). Both experimental and theoretical facts demonstrate that the mixed valence system (1+) is a delocalized one, and it can be classified as a Class III system according to the Robin & Day classification.
Mac-Leod Carey,Morales-Verdejo,Mu?oz-Castro,Burgos,Abril,Adams,Molins,Cador,Chávez,Manríquez,Arratia-Pérez,Saillard
p. 1137 - 1143
(2010/05/15)

Controlled storage of ferrocene derivatives as redox-active molecules in dendrimers
Dendritic polyphenylazomethines (DPA) could encapsulate ferroceniums by complexation of the electron-donating skeleton of the DPA imines. Upon addition of ferroceniums to a series of dendritic polyphenylazomethines (DPAGX, where X is the generation number, X = 1-4), the UV-vis spectra showed changes in a manner similar to that observed for the complexation of metal ions with DPAGX. Stepwise shifts in the isosbestic point were consistently observed with the number of imine groups in the first and second layers of the generation-4 dendrimer (DPAG4). DPAG2 and DPAG3 were also found to trap 6 equiv of ferroceniums. To investigate the complexation, UV-vis spectroscopy, 57Fe MoIssbauer spectroscopy, electrospray ionization-mass spectroscopy (ESI-MS), cyclic voltammetry (CV), and fluorescence spectroscopy were performed. We confirmed that neutral ferrocenes cannot complex with the imine group while ferroceniums can. Utilizing the redox property of ferrocenes, we were able to electrochemically control the encapsulation and release of ferrocenes into the DPA in a manner similar to redox-responsive proteins such as ferritin. In addition to ferrocenes, oligoferrocenes could also be trapped in the DPA. The biferrocene cation(1+) was particularly suitable for electrochemical switching due to its stable mixed valence condition. The terferrocene dication(2+) encapsulated into DPAG4 could be fabricated into a thin film, which exhibited the near-infrared absorption of an intervalence charge-transfer (IV-CT) band, pointing the way toward the use of such systems in material science.
Ochi, Yousuke,Suzuki, Mana,Imaoka, Takane,Murata, Masaki,Nishihara, Hiroshi,Einaga, Yasuaki,Yamamoto, Kimihisa
p. 5061 - 5069
(2010/06/14)

[3+2+1] Cycloaddition involving alkynes, CO and bridging vinyliminium ligands in diiron complexes: A dinuclear version of the Doetz reaction?
The vinyliminium complex [Fe2{μ-η1: η3-C(SiMe3)CHCN(Me)2}(μ-CO)(CO)(Cp) 2][SO3CF3] reacts with HCCR (R = CPh 2OH), affording a mixture of the 2,4,6-trisubstituted oxo-η5-cyclohexadienyl complex [Fe{η5-C 6H2O(NMe2)(SiMe3)(R)}(Cp)], the 2,6-disubstituted phenol C6H3R′(NMe2)OH (R′ = CHPh2) and 1,2,4-trisubstituted ferrocene [1-NMe 2-2-R-4-SiMe3-Fc]. The corresponding reaction with HCCR (R = CMe2OH) yields analogous products: [Fe{η5-C 6H2O(NMe2)(SiMe3)(R′)}(Cp)] (R′ = CMeCH2), the phenol C6H3R′ (NMe2)OH together with [1-NMe2-2-R-4-SiMe3-Fc].
Busetto, Luigi,Marchetti, Fabio,Mazzoni, Rita,Salmi, Mauro,Zacchini, Stefano,Zanotti, Valerio
p. 3327 - 3329
(2010/08/07)

Click syntheses of 1,2,3-triazolylbiferrocenyl dendrimers and the selective roles of the inner and outer ferrocenyl groups in the redox recognition of ATP2- and Pd2
This way and that: Triazolylbiferrocenyl dendrimers can be synthesized with up to 729 termini. Oxidation results in isolable mixed-valence dendrimers (see picture). In electrochemical studies, these species can recognize ATP 2- and PdII, and they can be used to stabilize Pd nanoparticle catalysts.
Djeda, Rodrigue,Rapakousiou, Amalia,Liang, Liyuan,Guidolin, Nicola,Ruiz, Jaime,Astruc, Didier
p. 8152 - 8156
(2011/02/23)

Synthesis, characterization and reactivity of dinuclear and trinuclear aluminum-bridged ferrocenophanes
Ferrocene derivatives bearing substituents with aluminum, in the 1,1'-positions, in the absence of donor ligands, possess rather unusual structural features. Starting from various dipyridine adducts of such 1,1'-disubstituted ferrocene derivatives, it pro
Wrackmeyer, Bernd,Klimkina, Elena V.,Milius, Wolfgang
p. 3163 - 3171
(2009/10/31)

Synthesis and reversible reductive coupling of cationic, dinitrogen-derived diazoalkane complexes
A series of cationic diazoalkane complexes [4-RC6H 4C(H)NNMo(N[t-Bu]Ar)3][AICI4], [1-R][AICI 4] (R = NMe2, Me,H,Br,CN; Ar = 3,5-C6H 3Me2) has been prepared
Curley, John J.,Murahashi, Tetsuro,Cummins, Christopher C.
p. 7181 - 7193
(2009/12/05)

Preparation and optical properties of fullerene/ferrocene hybrid hexagonal nanosheets and large-scale production of fullerene hexagonal nanosheets
The supramolecular nanoarchitectures, C60/ferrocene nanosheets, were prepared by a simple liquid-liquid interfacial precipitation method and fully characterized by means of SEM, STEM, HRTEM, XRD, Raman and UV-vis-NIR spectra. The highly crystal
Wakahara, Takatsugu,Sathish, Marappan,Miyazawa, Kun'ichi,Hu, Chunping,Tateyama, Yoshitaka,Nemoto, Yoshihiro,Sasaki, Toshio,Ito, Osamu
p. 9940 - 9944
(2009/12/08)

Reactivities of secondary phosphine selenides Cp(CO)2FeP(Se)(OR) 2: Formation of a diiodine charge transfer adduct and se-methylation
The organoiron-substituted phosphine selenides Cp(CO)2FeP(Se) (OR)2 (R = iPr (1a), nPr (1b), Et (1c)) were synthesized. The metalloligands, capable of reacting as nucleophiles toward Me3OBF4/sub
Chiou, Ling-Song,Fang, Ching-Shiang,Sarkar, Bijay,Liu, Ling-Kang,Leong, Max K.,Liu
p. 4958 - 4963
(2009/12/25)

Indirectly connected bis(N-Heterocyclic Carbene) bimetallic complexes: Dependence of metal-metal electronic coupling on linker geometry
Reaction of l,l',3,3'-tetra(tert-amyl)benzobis(imidazolylidene) (1) with 2 equiv of FcN3 or FcNCS afforded bisadducts [(FcN3) 2(1)] (2) or [(FcNCS)2(1)] (3), respectively (Fc = ferrocene). To the best of our kno
Tennyson, Andrew G.,Khramov, Dimitri M.,Varnado Jr., C. Daniel,Creswell, Philip T.,Kamplain, Justin W.,Lynch, Vincent M.,Bielawski, Christopher W.
p. 5142 - 5147
(2010/01/06)

Surprising isomer preference on IrIII, favoring facile H-C(sp3) bond cleavage
Species (PNP)Ir(X)(Y), where PNP = N(SiMe2CH2P tBu2)2-1 with X and Y halide, have a tBu group C-H bond heterolytically split by addition across the Ir-N bond. The Royal Society o
Tsvetkov, Nikolai P.,Laird, Matthew F.,Fan, Hongjun,Pink, Maren,Caulton, Kenneth G.
p. 4578 - 4580
(2010/01/06)

Alkylation of dinitrogen in [(HIPTNCH2CH2) 3N]Mo complexes (HIPT = 3,5-(2,4,6-i-Pr3C 6H2)2C6H3
In this paper we explore the ethylation of dinitrogen (employing [Et 3O][BArf4]; Arf = 3,5-(CF 3)2C6H3) in [HIPTN3N]Mo (Mo) complexes ([HIPTN3N]
Kupfer, Thomas,Schrock, Richard R.
p. 12829 - 12837
(2010/01/30)

Microwave synthesis of benchmark organo-iron complexes
Microwave-assisted reaction techniques have been applied to the formation of a variety of organo-iron species. The species synthesized include ferrocene and acetyferrocene, piano stool complexes such as CpFe(CO)2I, CpFe(PPh3)(CO)I, a
Garringer, Sean M.,Hesse, Andrew J.,Magers, John R.,Pugh, Kristapher R.,O'Reilly, Stacy A.,Wilson, Anne M.
p. 6841 - 6844
(2010/04/01)

How do redox groups behave around a rigid molecular platform? hexa(ferrocenylethynyl)benzenes and their "electrostatic" redox chemistry
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Diallo, Abdou K.,Ruiz, Jaime,Astruc, Didier,Daran, Jean-Claude,Varret, Francois
p. 3141 - 3145
(2009/09/25)

1,1' -Disubstituted ferrocenes with aluminum: Dinuclear and trinuclear dialumina[1.1]ferrocenophanes as pyridine adducts
Ferrocenes bearing dialkylaluminum substituent in the 1.1positions were characterized as their dipyridine adducts, and it was shown that they can be transformed into dinuclear alkylalumlnum-bridged [1.1]ferrocenophanes and finally into the trinuclear alum
Wrackmeyer, Bernd,Klimkina, Elena V.,Milius, Wolfgang
p. 3155 - 3162
(2009/10/17)

B-C bond cleavage of BArF anion upon oxidation of rhodium(I) with AgBArF. Phosphinite rhodium(I), rhodium(II), and rhodium(III) pincer complexes
A rare case of BArF anion cleavage (BArF- = tetrakis(3,5-bis(trifluoromethyl)phenyl)borate) by a metal complex is described. Reaction of the Rh(I) dinitrogen complexes 5a,b and 6a,b, based on the phosphinite pincer ligands {C6H4[OP( tBu)2]2} (2), with 2 equiv of AgBArF at room temperature resulted in B-C bond cleavage of one of the BArF anions and aryl transfer to afford the Rh(III) aryl complexes 7 and 8, respectively. The X-ray structure of 8 revealed a square-pyramidal geometry with a coordinated acetone molecule. The aryl transfer occurred as a result of electrophilic attack by unsaturated Rh(III) on one of the aryl rings of the BArF anion. Utilizing different solvents yielded the same product, except when CH3CN was used, in which case one-electron oxidation took place, yielding complex 9. Treatment of 6a,b with 1 equiv of AgX (X = BAr F, BF4, PF6) resulted in a one-electron oxidation to yield the paramagnetic Rh(II) complexes 9-11, respectively. Complex 11 was characterized by X-ray diffraction, revealing a mononuclear square-planar Rh(II) complex.
Salem, Hiyam,Shimon, Linda J. W.,Leitus, Gregory,Weiner, Lev,Milstein, David
p. 2293 - 2299
(2009/02/01)

Redox chemistry of the triplet complex (PNP)Co
Reaction of PNPCo, where PNP is (tBu2PCH 2SiMe2)2N-, with the persistent radical galvinoxyl, G, gives PNPCoIIG, a nonplanar S = 3/2 species. Reaction with PhCH2Cl or with 0.5 mol I2 gives PNPCoX (X = Cl or I, respectively), but additional I2, seeking CoIII, gives instead oxidation at phosphorus: (tBu2P(I)CH 2-SiMe2NSiMe2CH2PtBu 2)Col2. Hydrogen-atom transfer reagents fail to give PNPCoH, but H2 gives instead PNPCo(H)2, a result rationalized thermodynamically based on DFT calculations. Multiple equiv of PhSiH3 give a product of Co(V), where N/SiPh and P/Si bonds have formed. N2CH(SiMe3) gives a 1:1 adduct of PNPCo, whose metric parameters suggest partial oxidation above CoI; N 2CHPh gives a 1:1 adduct but with very different spectroscopic features. PhN3 reacts fast, via several intermediates detected below 0°C, to finally release N2 and form a CoI product where one phosphorus has been oxidized, PN(P=NPh)Co. Whereas PNPCo(N 3) resists loss of N2 on heating, one electron oxidation gives a rapid loss of N2, and the remaining nitride nitrogen is quickly incorporated into the chelate ligand, giving [tBu 2PCH2SiMe2NSiMe2-NP( tBu2)=CH2Co]. O2 or PhI=O generally gives products where one or both phosphorus centers are converted to its oxide, bonded to cobalt.
Ingleson, Michael J.,Pink, Maren,Fan, Hongjun,Caulton, Kenneth G.
p. 4262 - 4276
(2008/09/20)