- Zinc-Containing Radical Anions via Single Electron Transfer to Donor–Acceptor Adducts
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Reactions of [Cp*2Fe] with the Lewis acid [Zn(C6F5)2] in the presence of [(PhC(S)S)2], 9,10-phenanthrenedione or 4,5-pyrenedione yield the salt [Cp*2Fe][(PhC(S)S)Zn(C6F5/su
- Cao, Levy L.,Bamford, Karlee L.,Liu, Liu Leo,Stephan, Douglas W.
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- Unusual electronic effects imparted by bridging dinitrogen: An experimental and theoretical investigation
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We describe the preparation, structural and magnetic characterizations, and electronic structure calculations for a redox-related family of dinitrogen-bridged chromium acetylide complexes containing the [RC 2Cr(μ-N2)CrC2R]n+ (R = Ph-, iPr3Si-; n = 0, 1,2) backbone: [(dmpe)4Cr 2(C2Ph)2(μ-N2)] (1), [(dmpe) 4Cr2(C2SiiPr3) 2(μ-N2)] (2), [(dmpe)4Cr 2(C2SiiPr3)2(μ-N 2)]BArF4 (3), and [(dmpe)4Cr 2(C2SiiPr3)2(μ-N 2)](BArF4)2 (4). Compounds 3 and 4 are synthesized via chemical oxidation of 2 with [Cp2Co]+ and [Cp*2Fe]+, respectively. X-ray structural analyses show that the alteration of the formal Cr oxidation states does not appreciably change the Cr-N-N-Cr skeletal structures. Magnetic data collected for 2 and 4 are consistent with high-spin triplet and quintet ground states, respectively. The mixed-valent complex 3 exhibits temperature dependent magnetic behavior consistent with a quartet ? doublet twocenter spin equilibrium. Electronic structure calculations (B3LYP) performed on the full complexes in 2 and 4 suggest that the high-spin states arise from singly occupied orthogonal π* orbitals coupled with a variable occupation of dδ orbitals. Significant N-N and Cr-N π-bonding pins the occupation of the π manifold, leading to variable occupation of the dδ space. In contrast, mixed-valent 3 is not well described by a B3LYP hybrid density functional model. A [9,11] CAS-SORCI study on a simplified model of 3 reproduces the observed Hund's rule violation for the S = 1/2 ground state and places the lowest quartet 1.45 kcal/mol above the doublet ground state.
- Hoffert, Wesley A.,Rappe, Anthony K.,Shores, Matthew P.
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- Self-exchange reaction kinetics of metallocenes revisited: Insights from the decamethylferricenium-decamethylferrocene reaction at variable pressure
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Rate constants kex and volumes of activation ΔVex? have been obtained using 1H NMR for the self-exchange reaction of the [(η5-C5(CH3)5)2 Fe]+ hexafluorophosphate and tetrafluoroborate with [(η5-C5(CH3)5)2Fe] in acetone-d6 (ΔVex? = -8.6 ± 0.3 cm3 mol-1), dichloromethane-d2, and (semiquantitatively) in acetonitrile-d3. Under the experimental conditions, ion pairing was significant only in CD2Cl2, but even that produced only a minor reduction in kex and so had a negligible effect on ΔVex? (= -6.4 ± 0.2 cm3 mol-1 with PF6-). In all cases, ΔVex? is negative and consistent with a simple two-sphere activation model, rather than with that of Weaver et al. (Nielson, R. M.; McManis, G. E.; Safford, L. K.; Weaver, M. J. J. Phys. Chem. 1989, 93, 2152) in which the barrier crossing rate is limited by solvent dynamics. Similarly, the ~5-fold increase in kex on going from [(η5-C5H5)2Fe]+/0 to [(η5-C5(CH3)5)2 Fe]+/0 in acetone can be explained with the two-sphere model on the basis of the effects of reactant size on the solvent reorganization energy, without reference to solvent dynamics.
- Zahl, Achim,Van Eldik, Rudi,Matsumoto, Mitsuru,Swaddle, Thomas W.
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- ORGANOMETALLIC DERIVATIVES OF THE TRANSITION ELEMENTS IV. FERROCENES VIA THE REACTION OF IRON ATOMS WITH ALKYNES
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Iron atoms react with disubstituted alkynes to produce iron complexes and alkyne oligomers.The oligomers are cyclic trimers and/or cyclic tetramers of the starting alkynes.Structural characterization of iron complexes shows an unusual rearrangement to sub
- Simons, L. H.,Lagowski, J. J.
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- Catalytic photodefluorination of perfluoroalkanes to perfluoroalkenes with a ferrocene photosensitizer
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Perfluoroalkenes are obtained from perfluoroalkanes by photoinduced electron transfer from an organometallic photosensitizer, decamethylferrocene, in the polar solvent thf. In the presence of Zn, the reaction becomes catalytic in ferrocene because the dec
- Burdeniuc, Juan,Crabtree, Robert H.
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- Solvent Dynamical Effects in Electron Transfer: Comparisons of Self-Exchange Kinetics for Cobaltocenium-Cobaltocene and Related Redox Couples with Theoretical Predictions
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Rate constants, Kex, and activation parameters for the self-exchange of cobaltocenium-cobaltocene Cp2Co+/0, and the decamethyl derivative Cp'2Co+/0, in 13 organic solvents have been evaluated by using the proton NMR line-broadening technique with the objective of probing the influence of solvent dynamics upon the electron-transfer kinetics.Together with some corresponding measurements reported earlier for ferrocenium-ferrocene Cp2Fe+/0, additional measurements for the decamethyl derivative, Cp'2Fe+/0, and with corresponding data for Cp2Co+/0 electrochemical exchange, these results enable a systematic comparative examination to be made of the effects of solvent dielectric relaxation on the barrier-crossing frequency for such simple outer-sphere reactions.For the facile Cp'2Co+/0 couple the solvent dependence of the observed frequency factors, νn(obsd), extracted from the kex values by correcting for the solvent-dependent barrier height, ΔG*, is in approximate accordance with the relative frequency factors νos(calcd), predicted from the continuum model of overdamped solvent relaxation.The subunity (ca. 0.7-0.8) slope of the logarithmic νn(obsd) - ??os(calcd) plot for Cp'2C0+/0 self-exchange is consistent with a recent theoretical prediction of the combined effect of overdamped solvent motion and reactant vibrations (ref 2g).In a given solvent, the sequence of kex values is Cp'2Co+/0 > Cp2Co+/0 ca.Cp'2Fe+/0 > Cp2Fe+/0, with Cp2Co+/0 and Cp2Fe+/0 being about 10- and 100-folds lower, respectively, than Cp'2Co+/0 self-exchange.While these reactivity differences can be traced to variations in donor-acceptor orbital overlap, the solvent dependencies of kex for Cp2Co+/0 and Cp2Fe+/0 electron exchange nevertheless exhibit a strong influence from overdamped solvent relaxation.Marked deviations from the dielectric continuum predictions are seen, however, in several solvents.Thus the barrier-crossing frequencies in propylene carbonate, N-methylformamide, and especially methanol are substantially (4-100-fold) larger than expected from νos(calcd), implicating the presence of surprisingly rapid relaxation modes in these solvents.The solvent-dependent activation parameters also differ significantly from the expectations of conventional theoretical modes.
- Nielson, Roger M.,McManis, George E.,Golovin, Neal M.,Weaver, Michael J.
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- Tunable Band Gaps in MUV-10(M): A Family of Photoredox-Active MOFs with Earth-Abundant Open Metal Sites
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Titanium-based metal-organic frameworks (Ti-MOFs) have attracted intense research attention because they can store charges in the form of Ti3+ and they serve as photosensitizers to cocatalysts through heterogeneous photoredox reactions at the MOF-liquid interface. Both the charge storage and charge transfer depend on the redox potentials of the MOF and the molecular substrate, but the factors controlling these energetic aspects are not well understood. Additionally, photocatalysis involving Ti-MOFs relies on cocatalysts rather than the intrinsic Ti reactivity, in part because Ti-MOFs with open metal sites are rare. Here, we report that the class of Ti-MOFs known as MUV-10 can be synthetically modified to include a range of redox-inactive ions with flexible coordination environments that control the energies of the photoactive orbitals. Lewis acidic cations installed in the MOF cluster (Cd2+, Sr2+, and Ba2+) or introduced to the pores (H+, Li+, Na+, K+) tune the electronic structure and band gaps of the MOFs. Through the use of optical redox indicators, we report the first direct measurement of the Fermi levels (redox potentials) of photoexcited MOFs in situ. Taken together, these results explain the ability of Ti-MOFs to store charges and provide design principles for achieving heterogeneous photoredox chemistry with electrostatic control.
- Fabrizio, Kevin,Lazarou, Konstantinos A.,Payne, Lillian I.,Twight, Liam P.,Golledge, Stephen,Hendon, Christopher H.,Brozek, Carl K.
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- Influence of the redox active ligand on the reactivity and electronic structure of a series of Fe(TIM) complexes
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The redox properties of Fe and Zn complexes coordinated by an α-diimine based N4-macrocyclic ligand (TIM) have been examined using spectroscopic methods and density functional theory (DFT) computational analysis. DFT results on the redox series of [Zn(TIM*)]n and [Fe(TIM*)]n molecules indicate the preferential reduction of the α-diimine ligand moiety. In addition to the previously reported [Fe(TIM*)]2 dimer, we have now synthesized and characterized a further series of monomeric and dimeric complexes coordinated by the TIM ligand. This includes the five-coordinate monomeric [Fe(TIM*)I], the neutral and cationic forms of a monomeric phosphite adduct, [Fe(TIM*)(P(OPh) 3)] and [Fe(TIM*)(P(OPh)3)](PF6), as well as a binuclear hydroxy-bridged complex, [{Fe(TIM*)}2(μ-OH)] (PF6). Experimental and computational data for these synthetic compounds denote the presence of ferrous and ferric species, suggesting that the α-diimine based macrocycles do not readily support the formation of formally low-valent (M0 or MI) metal complexes as previously speculated. Magnetochemical, Moessbauer, electron paramagnetic resonance (EPR), and electronic spectral data have been employed to experimentally determine the oxidation state of the central metal ion and of the macrocyclic ligand (TIM*) in each compound. The series of compounds is described as follows: [FeII(TIM0)(CH3CN 2)]2+, SFe = ST = 0; [Fe 2.5(TIM2.5-)]2, ST = 1; [{Fe III(TIM2-)}2(μ-OH)]+, S Fe = 3/2, ST = 0; [FeIII(TIM2-)I], SFe = 3/2, ST = 1/2; [FeII(TIM 2-)(P(OPh3))], SFe = ST = 0; and [FeII(TIM1-)(P(OPh3))]1+/[Fe I(TIM0)(P(OPh3))]1+, ST = 1/2. The results have been corroborated by DFT calculations.
- Hess, Corinna R.,Weyhermueller, Thomas,Bill, Eckhard,Wieghardt, Karl
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- Ferro and Antiferromagnetic Exchange in Decamethylbimetallocenes
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With the aim of studying next-neighbor magnetic interactions in polymeric metallocenes the paramagnetic decamethylbimetallocenes (M′M′) have been chosen as most simple model compounds. They have been synthesized for vanadium, cobalt, and nickel (to yield V′V′, Co′Co′, and Ni′Ni′, respectively) by starting from dilithium and dithallium salts of the fulvalene dianion. The latter have been characterized by 13C NMR spectroscopy. Decamethylbiferrocene has been synthesized as a diamagnetic standard compound, and decamethylbicobaltocenium hexafluorophosphate, as a precursor to Co′Co′. While the methylated M′M′ species were stable when protected from air, the synthesis of the parent binickelocene (Ni′Ni′) was accompanied by the formation of the ternickelocene NiNiNi. According to 1H NMR spectroscopy NiNi and NiNiNi were antiferromagnetic and underwent ligand exchange to nickelocene and bisfulvalenedinickel. Unlike the usually green nickelocenes Ni′Ni′ was deep redviolet owing to a new band at 528 nm. Measurements of the magnetic susceptibility (Χm) and the magnetization established a rare example of ferromagnetic interaction within a purely organometallic compound for Co′Co′. By contrast. V′V′ and Ni′Ni′ were antiferromagnetic (J = -1.6 and -180 cm-1, respectively, with H = -JSA· SB). The 1H and 13C NMR spectra confirmed the expected structures of Co′Co′ and Ni′Ni′. while the synthesis of V′V′-d8 and 2H NMR spectroscopy were necessary to fully establish the vanadium compound, Temperature-dependent measurements of the 1H NMR signal shifts and of Χm yielded similar J values for Ni′Ni′. MO calculations were carried out for M′M′, and the results were converted into theoretical NMR spectra of the bridging fulvalene ligand depending on the spin-carrying MO. This allowed the full assignment of the NMR signals and showed that the spin is delocalized to more than one MO. The MOs were shown to have different magnetic coupling capabilities, and the different magnetic behavior of M′M′ was attributed to the near-degeneracy of the magnetic orbitals.
- Hilbig, Harald,Hudeczek, Peter,K?hler, Frank H.,Xie, Xiulan,Bergerat, Pierre,Kahn, Olivier
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- CONVERSION OF THE DIAMAGNETIC NONAMETHYLFERROCENYLCARBENIUM SALTS INTO THE PARAMAGNETIC SALTS OF BIS(NONAMETHYLFERROCENIUMYL)ETHANE
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Conversion of the diamagnetic salt of nonamethylferrocenylcarbenium primary cation into the paramagnetic salt of bis(nonamethylferroceniumyl)ethane has been studied by high-resolution NMR in solution and, mainly, by spin-lattice and spi-spin relaxation in
- Fedin, E. I,Blumenfeld, A. L.,Petrovskii, P. V.,Kreindlin, A. Z,Fadeeva, S. S.,Rybinskaya, M. I.
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- A Ferrocene-Based Dicationic Iron(IV) Carbonyl Complex
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The 16-valence electron species [Cp*2Fe]2+ (Cp=η-C5Me5), formally featuring a tetravalent iron ion, quantitatively binds CO in HF solution to form the stable, diamagnetic carbonyl species [Cp*2Fe(CO)]2+. This dication forms salts in the presence of AsF6? and SbF6? that were crystallographically characterized. The molecular structure in crystals of [Cp*2Fe(CO)](AsF6)2 displays cyclopentadienyl rings that are clearly not parallel and an equatorially bound η1-CO ligand. The formal oxidation state +IV of iron was investigated by 57Fe M?ssbauer spectroscopy and is supported by DFT computational analysis. A detailed spectroscopic characterization of the hitherto unprecedented high-valent iron carbonyl compounds is reported.
- Malischewski, Moritz,Seppelt, Konrad,Sutter, J?rg,Munz, Dominik,Meyer, Karsten
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- Cationic Copper Hydride Clusters Arising from Oxidation of (Ph3P)6Cu6H6
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Transfer of the first electron from (Ph3P)6Cu6H6 to Cp?2Fe+ is fast (k > 106 L·mol-1·s-1). Transfer of a second electron to the same oxidant has a much lower thermodynamic driving force and is considerably slower, with k = 9.29(4) × 103 L·mol-1·s-1. The second oxidation leads to the formation of [(Ph3P)6Cu6H5]+. The structure of [(Ph3P)6Cu6H5]+ has been confirmed by its conversion back to (Ph3P)6Cu6H6 and by microanalysis; X-ray diffraction shows that the complex is a bitetrahedron in the solid state. [(Ph3P)6Cu6H5]+ can also be prepared by treating (Ph3P)6Cu6H6 with MeOTf. With less than 1 equiv of Cp?2Fe+ as oxidant, (Ph3P)6Cu6H6 gives [(Ph3P)7Cu7H6]+ as the major product; X-ray diffraction shows a Cu6 octahedron with one face capped by an additional Cu. [(Ph3P)7Cu7H6]+ can also be prepared by treating (Ph3P)6Cu6H6 with [Cu(CH3CN)4]+ (along with 1 equiv of Ph3P), and can be converted back to (Ph3P)6Cu6H6 with base/H2.
- Liu, Shuo,Eberhart, Michael S.,Norton, Jack R.,Yin, Xiaodong,Neary, Michelle C.,Paley, Daniel W.
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- Deprotonation of decamethylferrocenium cation - new approach to alkyl group functionalization in transition metal complexes
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Deprotonation of decamethylferrocenium tetrafluoroborate (20 deg C, THF, tBuOK or iPr2NH, Et3N) proceeds via intermediate formation of nonamethylferrocenylmethyl radical and results in the products of butoxylation and amination of me
- Novikova, Lyudmila N.,Zagorevskii, Dmitrii V.,Ustynyuk, Nikolai A.
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- Reaction of the Transition Metal Hydrides [Cp*MH2] 2 (Cp* = η5-C5Me5; M = Fe, Ru) with BH3-THF to Yield Metallaboranes. Improved Kinetic Control Leads to Novel Ferraboranes
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The reactions of [Cp*MH2]2, Cp* = η5-C5Me5; M = Fe, Ru, with BH 3·THF have been explored. As with [Cp*RuCl 2]2, [Cp*RuH2]2 readily reacts with borane to generate nido-1,2-(Cp*RuH)2B 3H7. In contrast to the chloride, intermediates are detectible in the hydride reaction and product selectivity is higher. Benefits of the apparently lower reaction barrier appear in the reaction of [Cp*FeH2]2 with BH3·THF. The formation and isolation of the novel hydrogen-rich ferraborane arachno-1-Cp*FeB4H11 from the iron hydride contrasts with the production of pentamethylferrocene from a pentamethylcyclopentadienyl iron halide. This metastable ferraborane has been characterized spectroscopically as well as by reaction with Co 2(CO)8 to give a good yield of the more stable derivative nido-1-(Cp*Fe)-2-{Co(CO)3}B4H8 by metal fragment addition. The latter compound has been spectroscopically characterized in solution as well as in the solid state by a single-crystal X-ray diffraction study as an example of a mixed metal dimetallahexaborane.
- Peldo, Melanie A.,Beatty, Alicia M.,Fehlner, Thomas P.
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- Reaction of pentadienyl complexes with metal carbonyls: Synthetic, structural, and theoretical studies of metallabenzene π-complexes
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The reaction of open and half-open sandwich complexes of iron and ruthenium with metal carbonyls was studied. Three types of complexes could be isolated: Carbonyl-bridged iron-ruthenium dimers with cyclopentadienyl and pentadienyl terminal ligands, dimetallic iron carbonyl complexes with a bridging sigma;,π-coordinated pentadienyl ligand, and ruthenium complexes with one or two π-coordinated ruthenabenzene ligands. The latter are the first ever isolated bis(metallabenzene) π-complexes. The X-ray structures of C5Me5Ru(CO)4Fe-(C7H11), (μ-C7H10)Fe2(CO)6, and [(C8H11)Ru(CO)3]2 Ru are reported. Density functional calculations have been used to better understand the bonding in metallabenzene complexes. The electron localization function (ELF) clearly confirms metal-metal bonding interactions in the complexes studied. In particular, the bis(metallabenzene) complex 13 is found to exhibit a three-center bonding attractor in the ELF in its stable syn-eclipsed conformation but two two-center attractors in the ca. 30 kJ mol-1 less stable anti-eclipsed arrangement. The frontier orbitals of metallabenzenes exhibit very large participation of the ring metal. When metallabenzenes act as ligands to other metal fragments, direct metal-metal interactions are thus expected to be a general feature of the complexes, unless they are replaced by other interactions, e.g. by protonation. Natural population analyses suggest that the σ-donor abilities of the electron-rich d8 metallabenzene fragments predominate over their π-acceptor character.
- Effertz, Ulrike,Englert, Ulli,Podewils, Frank,Salzer, Albrecht,Wagner, Trixie,Kaupp, Martin
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- Fundamental electron-transfer and proton-coupled electron-transfer properties of Ru(iv)-oxo complexes
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Isolation and characterisation of RuIV(O) complexes were accomplished to investigate their fundamental electron transfer (ET) and proton-coupled ET (PCET) properties. Reorganisation energies (λ) in electron transfer (ET) and proton-coupled ET (PCET) from electron donors to the isolated RuIV(O) complexes have been determined for the first time to be in the range of 1.70-1.88 eV (ET) and 1.20-1.26 eV (PCET). It was suggested that the reduction of the λ values of PCET in comparison with those of ET should be due to the smaller structural change in PCET than that in ET on the basis of DFT calculations on 1 and 1e--reduced 1 in the absence and presence of TFA, respectively. In addition, the smaller λ values for the RuIV(O) complexes than those reported for FeIV(O) and MnIV(O) complexes should be due to the lack of participation of dσ orbitals in the ET and PCET reactions. This is the first example to evaluate fundamental ET and PCET properties of RuIV(O) complexes leading to further understanding of their reactivity in oxidation reactions.
- Kotani, Hiroaki,Shimomura, Hinatsu,Horimoto, Momoka,Ishizuka, Tomoya,Shiota, Yoshihito,Yoshizawa, Kazunari,Yanagisawa, Sachiko,Kawahara-Nakagawa, Yuka,Kubo, Minoru,Kojima, Takahiko
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- First 17-18-19-electron triads of stable isostructural organometallic complexes. The 17-electron complexes [Fe(C5R5)(arene)]2+ (R = H or Me), a novel family of strong oxidants: Isolation, characterization, electronic structure, and redox properties
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The 18-electron complexes [M(II)(C5R5)(arene)]+ (M = Fe: R = H or Me, arene = C6H6-nMe(n) (n = 0-6), C6H5NMe2, or C6Me5NH2; M = Ru: R = Me, arene = C6Me6) are oxidized to M(III) complexes between 0.92 and 1.70 V vs [FeCp2] according to a single-electron process that is reversible in SO2 if at least one of the rings is permethylated. The dinuclear complex [Fen(II)2(fulvalenyl)(C6Me6)][PF6]2 is oxidized in two one-electron reversible waves in SO2 separated by 0.38 V to the mixed-valence species trication and to the 34-electron dioxidized tetracation. Stoichiometric oxidation of the yellow complexes [Fe(II)Cp*(arene)][EX6] (EX6 = PF6 or SbCl6) is achieved by using SbCl5 in CH2Cl2 at 20 °C or SbF5 in SO2 at -10 °C or by Br2 + [Ag][SbF6] and gives the purple 17-electron complexes [Fe(III)Cp*(arene)][SbX6]2 (X = F or Cl) if arene = hexa-, penta-, and 1,2,4,5-tetramethylbenzene Z No oxidation is observed for complexes of less methylated arene ligands, which shows that the oxidation power of SbX5 is limited to 1.0 V vs [FeCp2] for monocations. The complex [Fe(III)Cp*(C6Me6)][SbCl6]2, 1[SBCl6]2, is also obtained by SbCl5 oxidation of the 19-electron complex [Fe1Cp*(C6Me6)], 1, at -80 °C. The 17-electron complexes are characterized by elemental analyses, ESR, Mossbauer, and UV/vis spectra, magnetic susceptibility, cyclic voltammetry, and quantitative single-electron reduction by ferrocene. The complex 1[SBCl6]2 is used as a very strong single-electron oxidant to also oxidize [Ru(bpy)3][PF6]2 to the 17-electron Ru(III) species and the neutral Cluster [FeCp(μ3-CO)]4 to its mono- and dications. The complex [Fe(II)Cp(C6Me6)][PF6] is a redox catalyst for the anodic oxidation of furfural on Pt in SO2 via the Fe(II)/Fe(III) redox system. Density functional theory (DFT) calculations on various 17-electron compounds [Fe(C5R5)(C6R6)](+/2+) (R = H, Me) and [FeCp(C6H5NH2)]2+, as well as on the isoelectronic complexes ferrocenium and [Fe(C6H6)2]3+ and their 18-electron parents, allowed a detailed comparison of the electronic structure, bonding, UV-visible spectra, and ionization potentials of these species. Although the nature of the HOMO is not always the same within the series of their 18-electron parents, all the computed 17-electron complexes have the same 2E2 ground state corresponding to the metallic (a1)2(e2)3 electron configuration. Full geometry optimizations lead to the prediction of their molecular structures for the lowest 2E2 and 1A1 states.
- Ruiz, Jaime,Ogliaro, Fran?ois,Saillard, Jean-Yves,Halet, Jean-Fran?ois,Varret, Fran?ois,Astruc, Didier
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- The special role of B(C6F5)3 in the single electron reduction of quinones by radicals
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In the presence of two molar equiv. of B(C6F5)3p-benzoquinone reacts with persistent radicals TEMPO, trityl or decamethylferrocene by single electron transfer to give doubly O-borylated benzosemiquinone radical anions with
- Tao, Xin,Daniliuc, Constantin G.,Knitsch, Robert,Hansen, Michael Ryan,Eckert, Hellmut,Lübbesmeyer, Maximilian,Studer, Armido,Kehr, Gerald,Erker, Gerhard
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p. 8011 - 8018
(2018/11/03)
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- Diverse Reactivity of ECp* (E = Al, Ga) toward Low-Coordinate Transition Metal Amides [TM(N(SiMe3)2)2] (TM = Fe, Co, Zn): Insertion, Cp* Transfer, and Orthometalation
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The reactivity of the carbenoid group 13 metal ligands ECp* (E = Al, Ga) toward low valent transition metal complexes [TM(btsa)2] (TM = Fe, Co, Zn; btsa = bis(trimethylsilyl)amide) was investigated, revealing entirely different reaction pattern
- We?ing, Jana,G?bel, Christoph,Weber, Birgit,Gemel, Christian,Fischer, Roland A.
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p. 3517 - 3525
(2017/03/24)
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- BASELESS NUCLEOTIDE ANALOGUES AND USES THEREOF
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A method of detecting a target nucleic acid.
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Paragraph 0099; 0100
(2014/05/07)
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- Three-Coordinate NiII: Tracing the Origin of an unusual, facile Si-C(sp3) bond cleavage in [(tBu2PCH 2SiMe2)2N]Ni+
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All attempts to synthesize (PNP)Ni(OTf) form instead (tBu 2PCH2SiMe2NSiMe2OTf)Ni(CH 2PtBu2). Abstraction of F- from (PNP)NiF by even a catalytic amount of B
- Fullmer, Benjamin C.,Fan, Hongjun,Pink, Maren,Huffman, John C.,Tsvetkov, Nikolay P.,Caulton, Kenneth G.
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p. 2571 - 2582
(2011/04/22)
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- Synthesis and reactions of novel triply thiolate-bridged diiron complexes [Cp*Fe(μ2-SR)3FeCp*] (Cp* = η5-C5Me5; R = Et, Ph)
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The novel thiolate-bridged diiron complexes [Cp*Fe(μ2- SR)3FeCp*] (1, R = Et; 2, R = Ph) have been obtained by the reaction of [Cp*FeCl]2 with LiSEt or LiSPh in THF. Treatment of 1 with CO or CNtBu in THF gives
- Chen, Yanhui,Zhou, Yuhan,Qu, Jingping
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p. 666 - 671
(2009/01/30)
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- New racemic planar-chiral metalloligands derived from donor-substituted indenes: A synthetic, structural, and catalytic investigation
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The synthesis and characterization of a new family of (η5- indenyl)MLn complexes (MLn = Mn(CO)3, Cp*Ru, or Cp*Fe; Cp* = η5-C5Me 5) derived from 3-PiPr2-indene, 1-P iPr2-2-NMe2-indene (1a[H]), or 1-P(S) iPr2-2-NMe2-indene (1b[H]) are described. Lithiation of 1b[H] followed by treatment with BrMn-(CO)5, 0.25 equiv of [Cp*RuCl]4, or Cp*Li/FeCl2 provided the corresponding (η5-1b)MLn complexes (MLn = Mn(CO)3, 2a, 96%; Cp*Ru, 2b, 87%; or Cp*Fe, 2c, 55%). Similarly, treatment of 1a[Li] with 0.25 equiv of [Cp*RuCl]4 or Cp*Li/FeCl2 provided the corresponding (η5-1a) MLn complexes (MLn = Cp*Ru, 3b, 74%; or Cp*Fe, 3c, 62%). Whereas combination of 3b and 0.5 equiv of [(COD)RhCl]2 afforded [(COD)Rh(κ2-P,N-3b)]+Cl- ([4b]+Cl-; 49% isolated yield), under similar conditions 3c was observed to undergo a decomposition reaction resulting in the formation of the zwitterionic complex (COD)Rh(κ2-P,N-1a) (5; COD = η4-1,5-cyclooctadiene). Each of 3a-c was observed to react cleanly with [(COD)Rh(THF)2]+BF4- (prepared in situ) to give the corresponding [(COD)Rh(κ2-P,N- 3a-c)]+BF4- complex ([4a-C]+BF 4-; 87%, 96%, and 89% isolated yield, respectively). Whereas lithiation of 3-Pi-Pr2-indene followed by the addition of BrMn(CO)5 generated a complex mixture of products, similar reactions employing 0.25 equiv of [Cp*RuCl]4 or Cp*Li/FeCl2 afforded 6b or 6c in 98% and 43% yield, respectively. Treatment of 6b with 0.5 equiv of [(COD)RhCl]2 allowed for the isolation of (COD)RhCl-(κ1-P-6b) 7 in 96% isolated yield. Each of [4a-C]+BF4- proved to be an active catalyst for addition of pinacolborane to styrene, with the observed regioselectivity being dependent on the nature of the η5- coordinated metal fragment, as well as the solvent employed. Single-crystal X-ray diffraction data for 2a, 2b, 2c, 3b, [4c]+BF4 -, and 7 are provided.
- Wechsler, Dominik,Ranking, Matthew A.,McDonald, Robert,Ferguson, Michael J.,Schatte, Gabriele,Stradiotto, Mark
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p. 6418 - 6427
(2008/10/09)
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- Reductive N-N bond cleavage of diphenylhydrazine and azobenzene induced by coordinatively unsaturated Cp*Fe{N(SiMe3)2}
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The coordinatively unsaturated iron(II) amido complex Cp* Fe{N(SiMe3)2} (1) serves as an efficient precursor for the cleavage of the N-N bond of diphenylhydrazine. The N=N bond of azobenzene was also found to be activated by 1 in the
- Ohki, Yasuhiro,Takikawa, Yuko,Hatanaka, Tsubasa,Tatsumi, Kazuyuki
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p. 3111 - 3113
(2008/10/09)
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- Insertion of pyridine into an iron-silicon bond and photochemical conversion of the insertion product Cp*(OC)Fe{η3(C,C,C)- C5H5NSiMe2NPh2} to a sandwich compound
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Irradiation of Cp*(OC)2FeSiMe2ERn (ERn = NPh2, NMe2, OMe) in the presence of pyridine affords Cp*(OC)(C5H5N)FeSiMe 2ERn, which are converted to Cp*(OC) Fe{η3(C,C,C)-C5H5NSiMe2ER n} upon mild heating via insertion of pyridine into the iron-silicon bond. This type of pyridine insertion does not proceed in the thermal reactions of Cp*(OC)(C5H5N)FeSiMe2R (R = Cl, Me) and the germanium analogues, Cp*(OC)(C5H5N) FeGeMe2ERn (ERn = NPh2, NMe 2, Me), even under more severe conditions. Treatment of Cp*(OC)(C5H5N)RuMe with HSiMe2NPh 2 at room temperature gives a 5:4 equilibrium mixture of Cp*(OC)(C5H5N)RuSiMe2NPh2 and Cp*(OC)HRu{κ2(Si,C)-SiMe2N(o-C 6H4)(Ph)}. Heating the mixture at 100°C does not afford an analogous insertion product, although the equilibrium is shifted to the side of the orthometalated compound. These results indicate that the insertion of pyridine is specific for the heteroatom-substituted silyliron(II) system. The insertion reaction is considered to proceed via the mechanism that involves the initial formation of an η2(N,C)-pyridine complex. Migratory insertion of pyridine into the iron-silicon bond accompanied by coordination of the terminal heteroatom then results in a congested transition state, leading to the formation of an η1-allyl intermediate, Cp*(OC)Fe-{κ2(C,E)-C5H5NSiMe 2ER2}. The formation of such a transition state is supported by kinetic analysis of the thermal conversion of Cp*(OC)(C 5H5N)FeSiMe2NPh2 to Cp*(OC)Fe{η3(C,C,C)-C5H5NSiMe 2NPh2}, giving activation parameters of ΔH* = 93(2) kJ mol-1, ΔS? = -53(6) J mol-1 K -1, and ΔG?298 K = 109(3) kJ mol -1. The η3-allyl complex is finally formed through dissociation of the amino part. Irradiation of Cp*(OC) Fe{η3(C,C,C)-C5H5NSiMe2NPh 2} causes dissociation of a carbonyl ligand to produce a new type of sandwich compound, Cp*Fe(η5-C5H 5NSiMe2NPh2).
- Iwata, Masatoshi,Okazaki, Masaaki,Tobita, Hiromi
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p. 6115 - 6124
(2008/10/09)
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- Synthesis, structures, and redox properties of mixed-sandwich complexes of cyclopentadienyl and hydrotris(pyrazolyl)borate ligands with first-row transition metals
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The synthesis, structures and redox properties of mixed-sandwich complexes of cyclopentadienyl and hydrotris(pyrazolyl)borate ligands with first-row transition metals were studied. Crystal structure determinations were performed for various complexes. Ana
- Brunker, Tim J.,Cowley, Andrew R.,O'Hare, Dermot
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p. 3123 - 3138
(2008/10/08)
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- Electron-transfer properties of Cp*FeP5: Evidence for dimerization reactions following both oxidation and reduction
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The redox reactions of Cp*Fe(η5-P5) (1; Cp= η5-C5Me5) have been characterized in nonaqueous solvents by electrochemical methods. As anticipated by analogy with ferrocene, 1 may be both oxidized and reduced in one-electron processes. Both processes are irreversible by cyclic voltammetry but reversible by bulk electrolysis. In CH2Cl2 complex 1 oxidizes initially to 17-electron 1+ (Ep,a = 0.57 V vs Fc), which rapidly equilibrates to give the dimeric dication [12]2+. An ESR spectrum attributed to 1+ is consistent with a d5 iron sandwich complex. A dimerization rate constant for 1+ of kD(17) = 1.4 × 104 M-1 s-1 was determined from cyclic voltammetry (CV) data. The dimeric dication quantitatively re-forms neutral 1 upon rereduction. Complex 1 undergoes reduction (E1/2 = -2.00 V) to 19-electron 1-, which also appears to dimerize in THF; kD(19) = ca. 6 × 105 M-1 s-1. Reoxidation of the diamagnetic dimer [12]2- regenerates 1. The shifts in potential induced when replacing a cyclopentadienyl ring by a pentaphosphacyclopentadienyl ring, explicable in terms of the weaker electron-donating ability of the latter, are greater for the reductions than the oxidations, implying an increased P5 character to the LUMO of 1 compared to the HOMO. Possible structures of the dimeric ions are discussed in terms of known structural analogues and previously published molecular orbital descriptions.
- Winter, Rainer F.
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p. 1827 - 1833
(2008/10/08)
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- X-ray crystal structures and the facile oxidative (Au-C) cleavage of the dimethylaurate(I) and tetramethylaurate(III) homologues
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Dimethylaurate(I) has been prepared as the crystalline tetrabutylammonium salt for comparison with the known tetramethylaurate(III) analogue. The linear structure of dimethylaurate(I) and the square-planar structure of tetramethylaurate(III) have both bee
- Zhu, Dimming,Lindeman, Sergey V.,Kochi, Jay K.
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p. 2241 - 2248
(2008/10/08)
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- Permethylferrocenium salt as a starting substance for the synthesis of r-substituted nonamethylferrocenes (R = CH2OMe, CH2+)
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Nonamethyl(methoxymethyl)ferrocene was formed in the reaction of a permethyl-ferrocenium salt with MeONa. Its structure was confirmed by mass-spectrometry, 1H and 13C NMR spectroscopy, by conversion into a salt of the known nonamethylferrocenylmethyl cation, and by independent synthesis.
- Kruglova,Kreindlin,Petrovskii,Rybinskaya
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p. 2451 - 2454
(2007/10/03)
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- Di-and triphospha-ferrocenes: Crystal and molecular structures of [Fe(η5-C5Me5)(η5- C3tBu3P2)] and of the adducts
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Synthesis and structural studies of the iron "sandwich" complex [Fe(η5-C5Me5)(η5-C3tBu3P2)] 1 are described. The lone pair electrons of the two adjacent phosphorus atoms of the C2tBu2P3 ring in the triphospha-ferrocene complex [Fe(η5-C5Me5)(η5-C2tBu2P3)] 2 can ligate to other metal centres. The results of single crystal X-ray structural studies of the molybdenum and tungsten pentacarbonyl η1-complexes [Fe(η5-C5Me5)(η5-C2tBu2P3)M(CO)5] (4: M = Mo, 5: M = W) are discussed; they form an isostructural series with the previously reported chromium complex. The starting material 2 reacts with [(C5H4Me)(CO)2Mn(THF)] to form the adduct [Fe(η5-C5Me5)(η5-C2tBu2P3)Mn(CO)2(η5-C5H4Me)] 6. The phenyl-substituted di-and triphosphacyclopentadienides [Na(DME)3][C3Ph3P2] and [Na(DME)3][C2Ph2P3] (DME = 1,2-dimethoxyethane) react with ferrous chloride and Li[C5Me5] to give the 'sandwich' compounds [Fe(η5-C5Me5)(η5-C3Ph3P2)] 9 and [Fe(η5-C5Me5)(η5-C2Ph2P3)] 10. The latter reacts with W(CO)5(THF) to yield the η1-complex [Fe(η5-C5Me5)(η5-C2Ph2P3)W(CO)5] 11.
- Müller, Christian,Bartsch, Rainer,Fischer, Axel,Jones, Peter G.,Schmutzler, Reinhard
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p. 141 - 148
(2007/10/03)
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- A simple route to FeCpCp′
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A new method for the synthesis of the mixed-ligand compound FeCpCp′ (where Cp′ denotes the pentamethyl cyclopentadienyl group) is described from the reaction of a solution of NaCp′ and LiCp with FeCl2 in THF. The mixture of products includes FeCp2, FeCpCp′ and FeCp2′ in approximately a 1 : 3 : 1 mole ratio. Partial oxidation of the mixture leads to preferential precipitation of the ferricinium salts of the derivatives with the most negative reduction potentials. Subsequent treatment with a reducing agent regenerates the ferrocenes. Implementation of a couple of redox cycles allows the isolation of pure samples of each product, including FeCpCp′. Extension of the method to the preparation of other unsymmetrical ferrocenes is straightforward so long as there is a modest spread in the reduction potentials of the components. The development of new synthetic methods is worthwhile because substituted ferrocenes are useful reagents in studies of electron-transfer processes. The method described herein is attractive because it is quite simple and adaptable to large-scale preparations.
- Cunningham, Kurstan L.,McMillin, David R.
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p. 1673 - 1675
(2008/10/09)
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- Transfer of a cyclo-E5 Ligand (E = P, As) from an Iron to a Ruthenium and an Osmium Center
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The thermolysis of 5-E5)> (1) and 2> (2, 3) affords by cyclo-E5 transfer the sandwich complexes 5-E5)> (4a, b: M = Ru, E = P, As; 4c: M = Os, E = P).The crystal-structure analysis of 5-P5)> (4c') confirms its sandwich-type structure. - Key Words: cyclo-E5 ligands (E = P, As) / Transfer reaction / Iron complexes / Ruthenium complexes / Osmium complexes / Sandwich complexes
- Rink, Barbara,Scherer, Otto J.,Wolmershaeuser, Gotthelf
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- Syntheses and structures of diruthenium triple-decker complexes with bridging 1,2,4-triphospholyl and 1-arsa-3,4-diphospholyl anions
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Yellow-brown oils, characterized spectroscopically as [Cp*Ru(η5-C2-t-Bu2P3)], 11, and [Cp*Ru(η5-C2-t-Bu2AsP2)], 12, were isolated from the reaction of [Cp*Ru(CH3CN)3][PF6], 6, with [Li(C2-t-Bu2P3)], 2, or [Li(C2-t-Bu2AsP2)], 4, respectively. Both 11 and 12 reacted further with 6 to give the triple-decker complexes [Cp*Ru(μ-η5:η5-C2-t-Bu 2P3)RuCp*][PF6], 7, and [Cp*Ru(μ-η5:η5-C2-t-Bu 2AsP3)RuCp*][PF6], 8, in which the triphospholyl or arsadiphospholyl anions bridge two ruthenium centers. Both 7 and 8 have been characterized by single-crystal X-ray crystal structure determinations. Crystal data for C30H48F6P4Ru2, 7: M = 848.7, P212121, a = 12.642(9) A?, b = 15.151(10 A?, c = 18.176(10) A?, V = 3481.4 A?3, Dcalcd = 1.62 g cm-3 (Z = 4) μ = 10.8 cm-1 for Mo Kα radiation (λ = 0.7107 A?), final R = 0.055, Rw = 0.057, from 2716 observed reflections (3437 measured). Data for C30H48AsF6P3Ru2, 8: M = 892.7, P212121, a = 12.650(9) A?, b = 15.147(8) A?, c = 18.111(10) A?, V = 3470.1 A?3, Dcalcd = 1.71 g cm-3 (Z = 4) μ = 19.9 cm-1 for Mo Kα radiation (λ = 0.7107 A?), final R = 0.049, Rw = 0.053, from 2760 observed reflections (3430 measured). Attempts to prepare mixed-metal triple-decker complexes by reacting [Fe(η5-C5R5)(η5-C 2-t-Bu2P3)] (R = H, 14a; R = Me, 14b] or [Fe(η5-C5R5)(η45-C 2-t-Bu2AsP2)] (R = H, 15a; R = Me, 15b) with 6 were unsuccessful. Likewise when either 14a or 15a is treated with 6 the intermediate complexes [Fe(η5-C5H5)(η5-C 2-t-Bu2P3)RuCp*(CH3CN) 2][PF6], 17, or [Fe(η5-C5H5)(η5-C 2-t-Bu2AsP2)RuCp*(CH3-CN) 2][PF6], 18, were isolated and spectroscopically characterized. When these were heated in nitromethane, a ring transfer occurred and the triple-decker species 7 or 8 was observed. Similar reactions involving 14b or 15b led directly to 7 or 8 without detection of any intermediate complexes.
- Hitchcock, Peter B.,Johnson, Julian A.,Nixon, John F.
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p. 4382 - 4389
(2008/10/09)
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- Pentamethylcyclopentadienylbis(ethene)iron - a 17e Halfsandwich Complex with Easily Displaceable Ethene Ligands
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The new room temperature stable halfsandwich complex Cp*Fe(tmeda)Cl (2) has been synthesized by the 1:1 reaction of FeCl2(thf)1.5 with LiCp* in a mixture of THF and TMEDA at -30 deg C. 2 is an ideal starting material for the synthesis of a wide range of new iron complexes.Treatment of 2 with lithium sand in THF in the presence of COD are ethene followed by the addition of TMEDA yields the ferrates (3) or (4).By delithiation with dichloroethane, 3 and 4 can be transformed into the novel 17e iron complexes Cp*Fe(cod) (5) and Cp*Fe(C2H4)2 (6). 6 is extremely labile.Since the ethene ligands can be easily displaced, the title compound is a synthetically valuable source of the Cp*Fe fragment.Whereas the photochemically generated 17e dicarbonyl species CpFe(CO)2 rapidly recombines to give the dimer 2, the isoelectronic 6 is stable in ethene saturated pentane for several days at 0 deg C.Without the stabilizing effect of ethene (in pure pentane or under vacuum), 6 loses ethene to give the dinuclear complex (Cp*Fe)2(C2H4)2 (8) irreversibly.The structure of 8 has been characterized by X-ray analysis. - Keywords: Bis(ethene)iron, Halfsandwich, Dinuclear Iron Complex
- Jonas, Klaus,Klusmann, Peter,Goddard, Richard
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p. 394 - 404
(2007/10/02)
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- Synthesis and Characterisation of the Mixed-sandwich Complex closo- and its Charge-transfer Salts; Crystal Structure of (1+)(.1-)*CH2Cl2 (ddq = 2,3-dichloro-5,6-dicyano-p-benzoquinone)
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The mixed-sandwich ferracarborane complex closo- has been synthesised and characterised by cyclic voltammetry, infrared, 1H and 11B NMR spectroscopy.This complex forms stable 1:1 charge-transfer salts with 2,3-dichloro-5,6-dicyano-p-benzoquinone (ddq) and 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane.Both salts are paramagnetic between 5 and 300 K with Weiss constants of -0.9 and -0.7 K respectively.The organic radical anions do not contribute to the bulk magnetic susceptibilities of these salts.Single-crystal X-ray diffraction analysis of the ddq salt shows that the ddq(.1-) anions form isolated stacked dimers within which there is a short interplanar separation of 2.90 Angstroem.Short S...O contacts (3.15 Angstroem) occur between the (1+) cations and the quinoidal oxygen atoms of the anions.The room-temperature electrical conductivity of single crystals of the ddq salt is less than 1E-7 S cm-1.
- Yan, Yaw-Kai,Mingos, D. Michael P.,Mueller, Thomas E.,Williams, David J.,Kurmoo, Mohamedally
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p. 2509 - 2514
(2007/10/03)
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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
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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
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p. 175 - 186
(2007/10/02)
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- Molecular second-order optical nonlinearities of metallocenes
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The nonresonant quadratic molecular hyperpolarizabilities of several ferrocene and ruthenocene derivatives were studied by dc electric-field-induced second-harmonic generation (EFISH) experiments using fundamental radiation at 1.91 μm, Hyperpolarizabilities approaching that of 4-(dimethylamino)-4′-nitrostilbene (DANS) were observed, indicating that the ferrocene moiety can act as an effective donor. It was found that the dipole projections of the β tensors of ferrocene complexes are comparable to those of methoxyphenyl systems with similar acceptors. Thus, (E)-ferrocenyl-4-(4-nitrophenyl)ethylene (5) has a β value of 31 × 10-30 esu whereas 4-methoxy-4′-nitrostilbene has a value for β of 29 × 10-30 esu. Replacement of the iron atom with ruthenium, which has a higher ionization potential, leads to a reduction in β relative to 5. Replacement of a cyclopentadienyl ring with a pentamethylcyclopentadienyl ring leads to increased nonlinearity.
- Calabrese, Joseph C.,Cheng, Lap-Tak,Green, Jennifer C.,Marder, Seth R.,Tam, Wilson
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p. 7227 - 7232
(2007/10/02)
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- Complexes with Sterically Demanding Ligands, II. - Synthesis and Structure of 1,1',2,2',4,4'-Hexakis(trimethylsilyl)ferrocene
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Reaction of iron(II) halides FeX2 (X = Cl, Br, I) with tris(trimethylsilyl)cyclopentadienyllithium Li at -40 deg C yields 1,1',2,2',4,4'-hexakis(trimethylsilyl)ferrocene, Fe5-C5H2(SiMe3)3>2 (2).Preparation of two mixed ferrocene derivatives Fe(η5-C5R5)5-C5H2(SiMe3)3> (R = H, 3; R = Me, 4) bearing one tris(trimethylsilyl)cyclopentadienyl ligand is also reported.An X-ray structure determination of 2 confirms the sandwich structure with significantly long Fe-C(ring) distances of average 2.082(1) Angstroem and virtually eclipsed five-membered rings.According to variable-temperature 1H- and 13C-NMR spectroscopic analysis, 2 shows in solution a hindered rotation of the two cyclopentadienyl rings around the metal-ligand vector (Δ(excit.) = 11.0 kcal/mol).
- Okuda, Jan,Herdtweck, Eberhardt
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p. 1899 - 1906
(2007/10/02)
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- Analysis of Substituted Ferrocenes by Infrared Spectroscopy
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The i.r. spectra of substituted ferrocenes were investigated to determine and analyse the appropriate ring-metal stretching force constants.Assignment of the ring-mode vibrations is attempted.
- Phillips, Leonidas,Lacey, Anthony R.,Cooper, Mervyn K.
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p. 1383 - 1392
(2007/10/02)
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- PENTAMETHYLCYCLOPENTADIENYL-UEBERGANGSMETALL-KOMPLEXE X. HALBSANDWICHKOMPLEXE DES Fe UND Ni ALS REAKTIVE ZWISCHENPRODUKTE
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Reaction of NiX2*DME (X=Cl, Br; DME=1,2-Diemthyoxyethane) with Cp'Li (Cp'-η5-C5Me5) in THF at -10 deg C yields as intermediates dimeric halogeno complexes 2 (1) as shown by mass spectroscopy. 1 reacts with neutral and anionic donor lig
- Koelle, U.,Fuss, B.,Khouzami, F.,Gersdorf, J.
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