- 'Salted' iron pentacarbonyl: Molecular isolation in alkali halide solids
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The conditions for single-molecule isolation of iron pentacarbonyl by codeposition from vapor phase onto a cold substrate with excess alkali halide vapor have been established. The photochemistry of thus 'salted' Fe(CO)5 has been investigated a
- Kirkor,David,Michl
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- Reaction of (chlorophosphine)iron tetracarbonyl complexes with aluminum chloride. Iron tetracarbonyl complexes of two-coordinate phosphorus cations
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The (chlorophosphine)iron tetracarbonyl complexes Me2NP(Cl)2Fe(CO)4, (Et2N)2P(Cl)Fe(CO)4, (i-Pr2N)2P(Cl)Fe(CO)4, [(Me3Si)2N]2/su
- Cowley,Kemp,Wilburn
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- Solid-state nuclear magnetic resonance spectroscopic and quantum chemical investigation of 13C and 17O chemical shift tensors, 17O nuclear quadrupole coupling tensors, and bonding in transition-metal carbonyl complexes and
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The carbon-13 and oxygen-17 nuclear magnetic resonance spectroscopic shielding behavior, as well as the oxygen-27 nuclear quadrupole coupling constants (NQCC), in the four metal-CO systems Fe(CO)5, Fe2(CO)9, Ni2
- Salzmann, Renzo,Kaupp, Martin,McMahon, Michael T.,Oldfield, Eric
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- Cucurbit[8]uril-based inclusion compounds containing iron(II), cobalt(III), and nickel(II) complexes with cyclam and cyclen as guest molecules: Synthesis and crystal structures
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New inclusion compounds containing iron(II), cobalt(III), and nickel(II) complexes with the cyclic polyamine ligands cyclam and cyclen in the macrocyclic cavitand cucurbit[8]uril (CB[8]) were obtained: {trans-[Fe(Cyclam)(CO)(OCHO)] @CB[8]}Cl ? 15H2O, {cis-[Co(Cyclen)(H2O)Cl]@CB[8]} Cl2 ? 20H2O, and {cis-[Ni(Cyclen)(H 2O)Cl]@CB[8]}Cl ? 12H2O. According to X-ray diffraction data, the complexes are in the cavity of each CB[8] molecule. The complexes of the above molecular formulas were isolated in the solid state as supramolecular compounds with CB[8] and structurally characterized for the first time.
- Kovalenko,Mitkina,Geras'Ko,Samsonenko,Naumov,Fedin
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- Reactions of N-(2-thienylmethylidene)-2-thienylmethylamine derivatives with diiron nonacarbonyl (see abstract)
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The reaction of N-(2-thienylmethylidene)-2-thienylmethylamine (1) with Fe2(CO)9 under mild conditions in anhydrous benzene yields the iron carbonyl products 2, 3, and 4. Complex 2 is a cyclometallated complex Fe2(CO)6(R-C4 HS-CH2NCH2-C4H3S), in which the organic ligand is (μ-η1:η2-thienyl β-C, α, β-C-C; η1:η 1-(N))-coordinated to the diiron center. Complexes 3 and 4 are novel linear tetrairon complex isomers Fe4(CO)8 (μ-CO)2(R-C4HS-CH- NCH2-C4H3S)2, in which the two organic ligands are (μ-η1-thienyl β-C: η1-N;η2-thienylα, β-C-C:η2-C-N)-coordinated to two diiron centers, respectively. These complexes were well characterized spectrally. The molecular structures of 1a, 2a, 2b, 3a, and 3b have been determined by means of X-ray diffraction. The linear arrangement of the four iron atoms in the 66e clusters 3 and 4 is consistent with the closed valance molecular orbital (CVMO) theory. Complexes 3 and 4 may be viewed as consisting of a central Fe2(CO)2(μ-CO) 2 core to which two η5-azaferracyclopentadieny fragments are coordinated; hence 3 and 4 are isolobally-related analogues of [CpFe(CO)(μ-CO)]2. Thermal reaction of 3 or 4 in hexane, benzene, or acetonitrile leads to the decomposition of the complex. No interconversion between isomers 3 and 4 has been observed.
- Tzeng, Yu-Fun,Wu, Chih-Yu,Hwang, Wen-Shu,Hung, Chen-Hsiung
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- Observation of Photochemical Intermediates in the Low-Temperature Photolysis of Silica-Adsorbed Fe(CO)5
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The photochemistry of silica-adsorbed Fe(CO)5 has been examined at reduced temperatures with a frequency-tripled Nd:YAG laser (355 nm) as the light source.The only significant photoproduct observed by IR spectroscopy upon photolysis at temperatures between 200 and 300 K is Fe3(CO)12; no Fe(CO)9 is detected.Photolysis at 100 to 150 K also yields Fe3(CO)12, but another major product is formed as well.On the basis of IR spectra obtained in the carbonyl stretching region, this product is assigned as Fe(CO)4(SiO2), which denotes the species formed upon addition of a silica surface hydroxyl group or siloxane bridging oxo group to the primary photoproduct, Fe(CO)4.This species is a key intermediate in the photoinitiated conversion of Fe(CO)5 to Fe3(CO)12 in tis system.Photolysis experiments were also carried out at temperatures below 100 K, but here Fe(CO)5 apparently aggregates on the silica surface, complicating interpretation of the photochemistry.
- Trusheim, Mark R.,Jackson, Robert L.
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- Syntheses and structures of iron carbonyl complexes derived from N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine and N-(6-methyl-2-pyridylmethylidene)-2-thiolethylamine
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The reaction of N-(5-methyl-2-thienylmethylidene)-2-thiolethylamine (1) with Fe2(CO)9 in refluxing acetonitrile yielded di-(μ3-thia)nonacarbonyltriiron (2), μ-[N-(5-methyl-2-thienylmethyl)-η1:η1 (N);η
- Wu, Chih-Yu,Chen, Lih-Hau,Hwang, Wen-Shu,Chen, Huang-Shiuh,Hung, Chen-Hsiung
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- Organometallic Fe–Fe Interactions: Beyond Common Metal–Metal Bonds and Inverse Mixed-Valent Charge Transfer
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The compounds [Fe(CO)3(dRpf)]n+, n=0, 1, 2 and dRpf=1,1′-bis(dicyclohexylphosphino)ferrocene ([1]n+) or 1,1′-bis(diisopropylphosphino)ferrocene ([2]n+), were obtained as two-step reversible redox systems by photolytic and redox reactions. The iron–iron distance decreases from about 4 ? to about 3 ? on oxidation, which takes place primarily at the tricarbonyliron moiety. Whereas ferrocene oxidation is calculated to occur only in excited states, the near infrared absorptions of the mixed-valent monocations are due to an unprecedented “inverse” inter-valence charge transfer from the electron-rich iron(II) in the ferrocene backbone to the electron-deficient tricarbonyliron(I). Protonation of complex 1 results in the formation of the structurally characterized hydride [1H]BF4, which reacts with acetone to form the dication, 12+, and isopropanol. While the hydride [2H]BF4was found to be unstable, protonation of 2 in acetone resulted in the clean formation of 22+,formally a hydrogen transfer.
- Ringenberg, Mark R.,Schwilk, Max,Wittkamp, Florian,Apfel, Ulf-Peter,Kaim, Wolfgang
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- 1,3-Dipolar cycloaddition to the Fe-S=C fragment 20. Preparation and properties of carbonyliron complexes of di-thiooxamide. Reactivity of the mononuclear (di-thiooxamide)Fe(CO)3 towards dimethyl acetylenedicarboxylate
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Reaction of Fe2(CO)9 at room temperature in THF with the di-thiooxamides (L), S=C{N(R,R′)}-C{(R,R′)N}=S [R=Me, R′-R′=(CH2)2 (a); R=H, R′=iPr (b); R=H, R′=iPr (c), R=H, R′=benzyl (d); R=H, R′=H (e)], results for ligands a-d initially in the formation of the mononuclear σ-S, σ-S′ chelate complexes Fe(CO)3(L) (7a-d), which could be isolated in case of 7a and 7d. Under the reaction conditions, complexes 7a-d react further with [Fe(CO)4] fragments to give three types of Fe2(CO)6(L) complexes (8a-d) in high yields, depending on the di-thiooxamide ligand used together with traces of the known complex S2Fe3(CO)9 (14). The molecular structures of these complexes have been established by the single crystal X-ray diffraction determinations of 8a, 8b and 8d. In the reaction with ligand e the corresponding complex 7e was not detected and the well-known complexes 14 and S2Fe3(CO)9 (15) were isolated in low yield. In situ prepared 7a reacts in a slow reaction with 1 equiv. of dimethyl acetylene dicarboxylate in a 1,3-dipolar cycloaddition reaction to give the stable initial ferra [2.2.1] bicyclic complex 10a in 60% yield. In complex 10a an additional Fe(CO)4 fragment is coordinated to the sulfido sulfur atom of the cycloadded Fe-S=C fragment. When a toluene solution of 10a is heated to 50 °C it loses two terminal CO ligands to give the binuclear Fe-Fe bonded complex 11a in almost quantitative yield. The molecular structures of 10a and 11a have been confirmed by single crystal X-ray diffraction. Reaction of 7d at room temperature with 2 equiv. of dimethyl acetylene dicarboxylate results in the mononuclear complex 12d in 5% yield. The molecular structure of 12b has been established by single crystal X-ray diffraction and comprises a tetra dentate ligand with two ferra-sulpha cyclobutene, and a ferra-disulpha cyclopentene moiety. When the reaction is performed at 60 °C a low yield of 2,3,4,5-thiophene tetramethyl tertracarboxylate is obtained besides complex 12d.
- Siebenlist, Ron,Frühauf, Hans-Werner,Kooijman, Huub,Veldman, Nora,Spek, Anthony L,Goubitz, Kees,Fraanje, Jan
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- Iron, ruthenium, and osmium complexes supported by the bis(silyl) chelate ligand (9,9-dimethylxanthene-4,5-diyl)bis(dimethylsilyl): Synthesis, characterization, and reactivity
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The bis(silyl)-type bidentate ligand precursors xantsil-H2 (la) and 2,7-di-t-butylxantsil-H2 (1b) possessing the xanthene backbone were prepared by dilithiation of the 4,5-positions of 9,9-dimethylxanthene or 2,7-di-t-butyl-9,9-dimet
- Minglana, Jim Josephus G.,Okazaki, Masaaki,Hasegawa, Kenji,Luh, Lung-Shiang,Yamahira, Nobukazu,Komuro, Takashi,Ogino, Hiroshi,Tobita, Hiromi
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p. 5859 - 5866
(2008/10/09)
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- Low-valent α-diimine iron complexes for catalytic olefin hydrogenation
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A family of low-valent α-diimine iron complexes has been synthesized and their utility in catalytic olefin hydrogenation reactions evaluated. Reduction of the ferrous dichloride complex [ArN=C(Me)C(Me)=NAr]FeCl2 (Ar = 2,6-(CHMe2)2-C6H3) with sodium amalgam in benzene or toluene furnished the iron arene complexes, [ArN=C(Me)C(Me)=NAr]Fe(η6-C6H5R) (R = H, Me). The solid-state structure of the toluene adduct revealed a contracted carbon-carbon backbone, short iron-imine bonds, and elongated imine nitrogen-carbon distances, suggesting significant reduction of the α-diimine ligand. The analogous reduction in alkane solvents afforded the bis(α-diimine) complex [ArN=C(Me)C(Me)=NAr]2Fe, which has also been crystallographically characterized. The arene complexes and the bis(a-diimine) complexes are inactive for catalytic olefin hydrogenation. Performing the reduction in the presence of internal alkynes such as diphenylacetylene and bis(trimethylsilyl)acetylene furnished the alkyne adducts [ArN=C(Me)C(Me)=NAr]Fe(η2-RC=CR) (R = Ph, SiMe3 ). Analogous olefin complexes with 1,5-cyclooctadiene and cycloctene have also been isolated using similar reduction procedures. The olefin adducts provide more active precatalysts than the alkyne compounds for the hydrogenation of 1-hexene. In each case, formation of rfarene adducts serves as a major catalyst deactivation pathway.
- Bart, Suzanne C.,Hawrelak, Eric J.,Lobkovsky, Emil,Chirik, Paul J.
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p. 5518 - 5527
(2008/10/09)
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- Endo and exo cyclometallated iron carbonyl complexes derived from N-(N′-methyl-2-pyrrolylmethylidene)-2-thienylmethylamine
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The reaction of N-(N′-methyl-2-pyrrolylmethylidene) -2-thienylmethylamine (1) with Fe2(CO)9 in refluxing toluene gives endo cyclometallated iron carbonyl complexes 2 and 5, exo cyclometallated iron carbonyl complex 3, and unexpected iron carbonyl complex 4. Complexes 2, 3, and 5 are geometric isomers. Complex 5 differs from complex 2 in the switch of the original substituent from α to β position of the pyrrolyl ring, and the pyrrolyl ring bridges to the diiron centers in μ-(3,2-η1:η2) coordination mode in stead of μ-(2,3-η1:η2). In complex 4, the pyrrolyl moiety of the original ligand 1 has been displaced by a thienyl group, which comes from the same ligand. Single crystals of 2, 3, and 5 were subjected to the X-ray diffraction analysis. The major product 2 undergoes: (i) thermolysis to recover the original ligand 1; (ii) reduction to form a hydrogenation product, 6, of the original ligand; (iii) substitution to form a monophosphine-substituted complex 7; (iv) chemical as well as electrochemical oxidation to produce a carbonylation product, γ-butyrolactam 8.
- Jin, Shiau-Yi,Wu, Chih-Yu,Lee, Chen-Shiang,Datta, Amitabha,Hwang, Wen-Shu
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p. 3173 - 3183
(2007/10/03)
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- A novel facet of carbonyliron-diene photochemistry: The η4-s-trans isomer of the classical Fe(CO)3(η4-s-cis-1,3-butadiene) discovered by time-resolved IR spectroscopy and theoretically examined by density functional methods
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The photolysis of Fe(CO)3(η4-s-cis-1,3-butadiene) (1) and Fe(CO)4(η2-1,3-butadiene) (2), formerly studied in low-temperature matrixes, is reexamined in cyclohexane solution at ambient temperature using time-resolved IR spectroscopy in the v(CO) region. Flash photolysis of 2 (λexc = 308 nm) generates Fe(CO)3(η4-s-trans-1,3-butadiene) (5) as a transient product, which then rearranges to form the classical η4-s-cis-1,3-butadiene complex 1. Species 5, previously addressed as the coordinately unsaturated Fe(CO)3(η2-1,3-butadiene) (3), is also photogenerated from 1, in this case along with the very short-lived CO loss fragment Fe(CO)2(η4-1,3-butadiene) (τ ? = 17.3 kcal·mol-1) with nearly complete recovery of 1. According to density functional calculations at the BP86 level of theory, 5 resides in a distinct energy minimum, 20.3 kcal·mol-1 above 1 and separated from it by a barrier of 15.0 kcal·mol-1. Its computed structure involves a diene dihedral angle of 129°. Species 3 (with a diene dihedral angle of -150.1°), by contrast, is predicted to exist in a rather flat minimum, which makes it too short-lived for detection with our instrumentation. Flash photolysis of Fe(CO)5 generates the very short-lived (3(solv) species in addition to the familiar Fe(CO)4(solv) fragment (τ = 10-15 μs), Fe2(CO)9 being the ultimate product in the absence of potential trapping agents other than CO. Deliberate contamination of the system with water gives rise to the formation of Fe(CO)4(H2O) as a longer lived transient (ca. 1 ms). In the presence of 1,3-butadiene, both 2 and 5 appear almost instantaneously. The latter decays, again in the millisecond time range, with formation of 1, thus providing clear evidence of a single-photon route from Fe(CO)5 to 1 in addition to the established two-photon sequence via the monosubstituted complex 2.
- Bachler, Vinzenz,Grevels, Friedrich-Wilhelm,Kerpen, Klaus,Olbrich, Gottfried,Schaffner, Kurt
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p. 1696 - 1711
(2008/10/08)
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- 1,3-dipolar cycloaddition to the Fe-O=C fragment (see abstract)
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1,3-dipolar cycloaddition to the Fe-O=C fragment was investigated. First X-ray crystal structure of the initial bicyclo[2.2.1] adduct was also reported. The cycloaddition reaction of complexes with DMAD in the presence of PR3 (k: R = OMe; l: R = Ph) resulted without detectable intermediates in the formation of the Fe(CO)2PR3(butenolide) complexes.
- Siebenlist, Ron,Frühauf, Hans-Werner,Vrieze, Kees,Smeets, Wilberth J.J.,Spek, Anthony L.
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p. 5628 - 5641
(2008/10/08)
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- Reaction of tris(trimethylsilyl)silane with pentacarbonyliron
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Heating of pentacarbonyliron with tris(trimethylsilyl)silane results in liberation of hydrogen and formation of hexakis(trimethylsilyl)disilane. Photoinitiated reaction of the same compounds begins with oxidative addition of the silicon hydride to the iron complex with liberation of carbon(II) oxide. Subsequent transformations of the adduct lead to formation of bis(trimethylsilyl)silanediyltricarbonylhydrido(trimethylsilyl)iron which can be stabilized as an adduct with hexamethylphosphoramide.
- Semenov,Cherepennikova,Makarenko
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p. 910 - 912
(2007/10/03)
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- Organometallics of transition metals in supercritical carbon dioxide: Solubilities, reactions, catalysis
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Monomeric compounds of the type Cp2M (p.e. M = Fe, Co, Ni) are soluble in liquid or supercritical CO2 ( ScCO2 ) without any reaction with the solvent. The polymeric compounds zincocene or manganocene form with CO2 insoluble CO2 insertion products. As well homoleptic metal carbonyls as a number of ligand-stabilized metal carbonyls are also soluble in scCO2. Fe(CO)5 reacts photochemically in this solvent to Fe2(CO)9 and thermically to Fe3(CO)12. The highly reactive (cdt)Ni(0) (cdt: cyclododeca-1,5,9-triene) is soluble in liquid CO2. A reaction with the solvent could not been observed. Solved in scCO2 (cdt)Ni reacts thermically to form Ni after a short time. CpCo(cod) catalyzes slowly the cyclo-cooligomerization of hex-3-yne with acetonitrile to form 2,3,4,5-Tetraethyl-6-methylpyridine. Propargylic alcohol reacts under formation of cyclotetrameres with a selectivity of 90% using (cod)2Ni or (cdt)Ni as catalysts, hex-3-yne in and with carbon dioxide under selective formation of tetraethyl-2-pyrone when the catalyst system R3P/(cod)2Ni (R: Me, Et) is used. In situ IR measurements show that the catalytically active species will be desactivated by formation of nickel carbonyl complexes. The catalytic oxidation of cyclooctene to form cycloocteneoxid with t-BuOOH using Titan(IV)-isopropylate as soluble catalyst proceeds less selectively, however in the presence of Mo(CO)6 the epoxid is formed in good yields and in a highly selective reaction.
- Kreher, Ulf,Schebesta, Sebastian,Walther, Dirk
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p. 602 - 612
(2008/10/09)
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- Diiron Complex with Three Bridging Silyl Substituents
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The crystal structure of hexacarbonyl-μ-(chloromethylsilyl)-bisdiiron(Fe-Fe), , has been determined.The Fe-Fe distance is 2.705 (1) Angstroem and the Fe-Si distances are 2.322 (3) Angstroem.The combination of
- Simons, Richard S.,Tessier, Claire A.
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p. 1997 - 1998
(2007/10/02)
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- Preparation of novel alkylated ruthenium α-diimine complexes: Reactivity toward carbon monoxide and phosphines
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Ru2(CO)8(iPr-DAB) (1) reacts with MeI at room temperature to give Ru2(Me)(I)(CO)4(iPr-DAB) (2a), and a single-crystal X-ray structure determination of 2a has been obtained. Crystals of 2a are orthorhombic, space group Pbca, with unit-cell dimensions a = 16.2510 (10) ?, b = 13.2660 (10) ?, and c = 17.2410 (10) ?. The molecular structure consists of a Ru(Me)(CO)2 fragment and a Ru(CO)2 fragment, held together by an iodide bridge and a bridging α-diimine ligand. The DAB ligand is coordinated to the Ru(Me)(CO)2 fragment via both nitrogen atoms and to the Ru(CO)2 fragment via an η2 coordination of both imine bonds. Treatment of 2a with CO leads to substitution of the iodide bridge and the two coordinated imine bonds with the formation of Ru(Me)(I)(CO)2(iPr-DAB) (3a) and Ru(CO)5. This reaction, which is reversible, provides a new synthetic route for the preparation of monomeric methylated α-diimine complexes. Several other reaction routes for the formation of the complexes Ru(X)(Y)(CO)2(α-diimine) (X = Me, Y = I, α-diimine = iPr-DAB (3a); X = Me, Y = I, α-diimine = iPr-Pyca (3b); X = Y = I, α-diimine = iPr-DAB (3c); X = Y = I, α-diimine = iPr-Pyca (3d); X = Cl, Y = benzyl, α-diimine = iPr-DAB (3e)) are presented. Treatment of 2a with phosphines leads to substitution of only one coordinated imine bond, with the formation of Ru2(Me)(I)(CO)4(PR3)(iPr-DAB) (PR3 = PPh3 (4a), PMe2Ph (4b), P(OMe)3 (4c)). A single-crystal X-ray structure determination of 4b has been obtained, and crystal of 4b are monoclinic, space group P21/c, with unit-cell dimensions a = 7.2030 (10) ?, b = 21.907 (2) ?, c = 16.813 (3) ?, and β = 94.352 (13)°. The molecular structure of 4b consists of a Ru(Me)(CO)2 fragment and a Ru(CO)2(PMe2Ph) fragment which are bridged by an iodide atom and a 6e-donating σ(N)-μ2(N′)-η2(C=N)-bonded DAB ligand. Complexes 4a-c easily lose a carbonyl ligand to form Ru2(Me)(I)(CO)3(PR3)(iPr-DAB) (PR3 = PPh3 (5a), PMe2Ph (5b), P(OMe)3 (5c)), and this reaction is shown to be reversible. Upon treatment of 3a with Ru(CO)4 fragments complex 2a is formed in good yield. Furthermore, reaction of 3a with Fe(CO)4 fragments leads to the formation of the heteronuclear complex FeRu(Me)(I)(CO)4(iPr-DAB) (2b). In the presence of traces of water HFeRu(Me)(CO)5(iPr-DAB) (6) is produced as a side product. A single-crystal X-ray structure determination of 6 has been obtained and crystals of 6 are monoclinic, space group C2/c, with unit-cell dimensions a = 18.102 (4) ?, b = 8.2761 (6) ?, c = 25.131 (4) ? , and β = 90.627 (16)°. As in 4b the DAB ligand in 6 is σ(N)-μ2(N′)-η2(C=N)-coordinated to the bimetallic core, with the σ(N) coordination to the Ru center and the η2(C=N) coordination to the Fe center. The hydride ligand of 6 was found to be bridging the metal-metal bond. Finally, the monomeric diiodide complex 3c was reacted with Ru(CO)4 fragments to form Ru2(I)2(CO)4(iPr-DAB) (7).
- Kraakman, Marco J. A.,Vrieze, Kees,Kooijman, Huub,Spek, Anthony L.
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p. 3760 - 3773
(2008/10/08)
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- Reaction Kinetics of Coordinatively Unsaturated Iron Carbonyls Formed on Gas-Phase Excimer Laser Photolysis of Fe(CO)5
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The reactions of species produced on gas-phase excimer laser photolysis of Fe(CO)5 have been followed by transient infrared spectroscopy employing a diode laser probe.The initial photoproducts formed on 193-nm photolysis are identified as Fe(CO)2 and a product that is most likely Fe(CO).Both Fe(CO)2 and Fe(CO)3 are produced on 248-nm photolysis.Photolysis at 351 nm leads to the production of both Fe(CO)3 and Fe(CO)4.Species best assigned as excited states of Fe(CO)3 and Fe(CO)4 are observed to form as initial photoproducts following 248- and 351-nm photolysis, respectively.The magnitudes of the rate constants for reaction of the various coordinatively unsaturated metal carbonyls formed in this study with parent Fe(CO)5 or CO (summarized in Table I) are consistent with the hypothesis that spin-allowed reactions will be rapid while spin-disallowed reactions will be considerably slower.To provide further data in testing this hypothesis, the reaction of Fe(CO)4 with both O2 and H2 has been measured.
- Ryther, Robert J.,Weitz, Eric
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p. 9841 - 9852
(2007/10/02)
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- Use of solid-state 13C NMR spectroscopy to quantify the degree of asymmetry of bonding for semibridging CO groups in iron carbonyl complexes
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The solid-state 13C NMR spectra of some substituted iron carbonyl complexes have been analyzed to give values for the carbonyl carbon chemical shift tensor components. It is shown that the lowest frequency tensor component and the chemical shift anisotropy correlate with the degree of bonding asymmetry in double-bridging carbonyl groups, whereas the 13C isotropic chemical shift does not correlate. The correlations are proposed to form the basis for a method of estimating iron-carbon bond lengths for μ2-CO groups in this type of complex.
- Hawkes, Geoffrey E.,Sales, Keith D.,Aime, Silvio,Gobetto, Roberto,Lian, Lu-Yun
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p. 1489 - 1493
(2008/10/08)
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- Bis(diphenylphosphino)methane-assisted Synthesis of Iron-platinum and -palladium Clusters. Crystal Structures of and (dppm=Ph2PCH2PPH2)
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Reactions of (dppm=Ph2PCH2PPh2) complexes with carbonyl reagents afforded dppm-bridged Fe-M mixed-metal complexes: (1) was best obtained using , (2) by the reaction K, (4) by the reaction with Na2, and (5) by the reaction with Na2.Reactions of Pd with Na2 afforded (6; M=Pd) and (7; M=Pt) in high yields.Cluster (7) was shown to exist in two isomeric forms.The kinetic isomer, isolated pure at -20 deg C, contains a terminal Pd-bound carbonyl whereas the thermodynamic isomer has a terminal Pt-bound carbonyl ligand.A 1:1 ratio is observed at equilibrium.The cluster (3) was obtained quantitatively by reaction of (1) or with 1 or 2 equivalents of dppm.These reactions were shown to occur first by substitution of the Pt-bound carbonyl ligand.Low-yield interconversion of (1) and (2) was observed as a result of metal-exchange reactions.The structures of clusters (1) and (2) have been established by single-crystal X-ray diffraction studies.In (1) a Fe-Pt bond is bridged by the dppm ligand and Fe(1)-Fe(2) 2.740(2), Pt-Fe(1) 2.542(1), and Pt-Fe(2) 2.557(1) Angstroem.In (2) the Pt-Pt bond is bridged by the dppm ligand and Fe-Pt(1) 2.541(3), Fe-Pt(2) 2.541(4), and Pt(1)-Pt(2) 2.581(1) Angstroem.The i.r. and n.m.r. spectra (1H, 1H-31P>, and 31P-1H>) of the new compounds are reported and discussed.
- Braunstein, Pierre,Richert, Jean-Luc,Dusausoy, Yves
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p. 3801 - 3814
(2007/10/02)
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- A transient infrared spectroscopy study of coordinatively unsaturated osmium carbonyl compounds
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Transient infrared spectroscopy is used to study the coordinatively unsaturated osmium carbonyl fragments generated by 248-nm photolysis of gas-phase Os(CO)5. The nascent photoproducts, predominantly Os(CO)3 with some Os(CO)4, are highly reactive toward combination with both CO and Os(CO)5. The bimolecular rate constants for reaction of Os(CO)3 and Os(CO)4 with CO are 7.6 ± 0.9 and 5.5 ± 0.6 × 10-11 cm3 molecule-1 s-1, respectively. Infrared absorptions for a new unsaturated osmium species, Os2(CO)8, formed by reaction of Os(CO)3 with Os(CO)5, are assigned. The rate constant for this reaction is 2.7 ± 0.9 × 10-10 cm3 molecule-1 s-1, on the order of gas kinetic. The reactivities of the unsaturated osmium species are similar to those of the analogous ruthenium compounds and contrast with the reactivity of Fe(CO)4. The trends observed in the photochemistry of group 8 metal carbonyl complexes and the role of spin selection rules in the reactivity of these coordinatively unsaturated fragments are discussed. Continuing depletion of the Os(CO)5 parent after photolysis indicates that polynuclear osmium carbonyl clusters are formed.
- Bogdan, Paula L.,Weitz, Eric
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p. 639 - 644
(2007/10/02)
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- Uebergangsmetall-Heteroallen-Komplexe. XXII. Zweikernige Cobalt- und Eisen-Komplexe mit Bis(trifluormethyl)- und Bis(ethoxycarbonyl)thioketen als Liganden
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Co2(CO)8 reacts with the thioketene (CF3)2CCS to give a dinuclear compound 2 (6).Photolysis of (CF3)2CCS with Fe(CO)5 leads to two differing complexes of the type (9) and 2 (10).The dimeric thioketene (EtOOC)2CCSSCC(COOEt)2 reacts with Fe(CO)5 to give (13).The crystal structure of 9 has been determined by X-ray diffraction.
- Seitz, Karsten,Benecke, Joerg,Behrens, Ulrich
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p. 247 - 256
(2007/10/02)
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- SF6-Sensitized Infrared Photodecomposition of Fe(CO)5
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The SF6-sensitized infrared photodecomposition of Fe(CO)5 induced by a transversely excited atmospheric (TEA) CO2 laser has been studied.The decomposition of Fe(CO)5 proceeds via sequential decarbonylation after thermal equilibrium is attained through collisional V-V and V-T/R processes.Fe(CO)4(PF3) is formed as a dominant product at lower conversion in a mixture of SF6-Fe(CO)5- PF3, which indicates that the rate-determining process is the first decarbonylation of excited Fe(CO)5 into Fe(CO)4 and CO, and that Fe(CO)4 is trapped by PF3 to yield Fe(CO)4(PF3).In addition, Fe(CO)3(PF3)2, Fe(CO)2(PF3)3, and Fe(CO)(PF3)4 are formed progressively with increasing conversion of Fe(CO)5.The higher PF3-substituted iron complexes are formed by repeated series of thermal excitation, decarbonylation, and trapping by PF3.Final products are CO and iron particles, following the shot by shot stoichiometry of Fe(CO)5 --> Fe + 5CO.The iron particles are found to by γ-iron or austenite, (Fe-C)4F, including 0.75 wt percent carbon which has a mean particle size of 80 Angstroem and a face-centered-cubic structure.Variations of the decomposition probability by changing the irradiation parameters are qualitatively explained by changes of kinetic temperture in irradiated volume.The decomposition mechanism in SF6-sensitized infrared photolysis is compared with those in conventional pyrolysis, infrared multiple-photon decomposition, and uV photolysis.
- Majima, Tetsuro,Ishii, Tadahiro,Matsumoto, Yoshiyasu,Takami, Michio
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p. 2417 - 2422
(2007/10/02)
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- INFRARED SPECTROSCOPY OF EXCITED STATES AND TRANSIENTS IN PHOTOCHEMISTRY
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Flash photolysis with time-resolved IR detection is used in investigations of the primary photoreactions of chromium, molybdenum, tungsten, manganese, iron, and osmium carbonyl complexes, and of the ensuing transformations of transient products in room temperature solution.The method bridges the gap to spectral data obtained at low temperatures.It provides information which has previously been inaccessible, such as detailed structural information, and kinetic data in cases where the UV-visible absorptions of the species of interest overlap.Finally, excited-state IR spectroscopy has now become feasible for many organic compounds with the most recent instrumental set-up which reaches a time resolution of >=50 ns.
- Schaffner, Kurt,Grevels, Friedrich-Wilhelm
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- Transition Metal Complexations to Cyclic Organoboron Phosphorus Compounds
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The dimeric 4,5-diethyl-2,5-dihydro-2,2-dimethyl-3-organo-1-phenyl-1,2,5-phosphasilaboroles react with (ligand)transition metal compounds (CH3CN)3Cr(CO)3, Cr(CO)6; (CH3CN)3Mo(CO)3; (CH3CN)3W(CO)3; Fe(CO)5, Fe2(CO)9; Ru3(CO)12; C5H5Co(C2H4)2; Ni(C12H18) thermally or photochemically to form η1-P complexes 1-1a (X-ray analysis); (OC)5Mo-η1-1a; (OC)5W-η1-1a>, η2-C2 complexes 2-1a, (OC)5Cr-η2-1a'; (OC)5W-η2-1a, (OC)5W-η2-1a'> and mainly η4-C2PB complexes 4-1a; (OC)4Mo-η4-1a; (OC)4W-η4-1a; (OC)3Fe-η4-1a,b, (OC)3Fe-η4-1b'; (OC)3Ru-η4-1a,b, (OC)3Ru-η4-1b'; C5H5Co-η4-1a,b; Ni(η4-1a)2 (X-ray analysis), Ni2(η3, η4-1b)2>.In addition to these complexes the isomerized η4-C2PB complexes (OC)3Fe-η4-iso-1a,b and (OC)3Ru-η4-iso-1a,b are formed thermally by an exchange of the phenyl and ethyl substituents at the P and B atom. - The crystallized η1-P complexes (OC)5M-η1-2 (M = Cr, Mo, W) are formed photochemically followed by heating from the dimeric 4,5-diethyl-1,2,5,6-tetrahydro-2,2,3-trimethyl-1-phenyl-1,2,5-phosphasilaborin (2)2 and M(CO)6 (M = Cr, Mo, W). - The new transition metal complexes are compared by mass spectrometry and by the NMR data (1H, 13C, 11B, 29Si, 31P) with the corresponding transition metal complexes of the C2SiElB heterocycles (El = NR, S , Se).
- Koester, Roland,Seidel, Guenter,Boese, Roland,Wrackmeyer, Bernd
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p. 1941 - 1954
(2007/10/02)
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- THE COORDINATION OF ALKYNES TO FOUR METAL ATOMS IN SQUARE PLANAR CLUSTERS. CRYSTAL STRUCTURE AND CLUSTER CONTRACTION AND EXPANSION REACTIONS OF (η5-C5H5)2NiFe2(CO)6(μ4,η2-C2Ph2)
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The structure of the tetranuclear cluster (η5-C5H5)2NiFe2(CO)6(μ4,η2-C2Ph2) (Ia) has been determined by X-ray methods.Crystals of Ia are othorhombic, space group Pbca, with a 24.774(21), b 29.509(19), c 14.677(7) Angstroem, Z = 16; R = 0.063 for 3626 observed reflections.In the crystal structure of Ia two crystallographically independent but almost identical heteronuclear clusters are present, in which two Fe atoms and two Ni atoms are in slightly distorted square planar arrangement with the alkyne interacting with all four metals, through ? bonds to the Ni and ? bonds to the Fe atoms.The structural features of Ia are compared with those of related compounds, and a discussion is presented of the square planar and flattened butterfly clusters reported to date, some of which are formally unsaturated.The reactions of Ia (a formally 62 electron cluster which can be described in skeletal electron counting terms as a 6-vertex 8-skeletal pair nido-pentagonal bipyramid) with donor ligands (CO, PR3, alkynes) and metal fragments have been examined.No evidence of Lewis acidity normally associated with unsaturation was found, but cluster expansion reactions generating pentametallic complexes from Ia via completion of the pentagonal bipyramid have been observed.The synthesis and spectroscopic characterization of these new complexes are described.
- Sappa, Enrico,Lanfredi, Anna Maria Manotti,Predieri, Giovanni,Tiripicchio, Antonio,Carty, Arthur J.
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p. 365 - 384
(2007/10/02)
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- Reactions of 2,3-Bis(carbomethoxy)-9,10-dichlorobicyclo-deca-2,5-diene with Fe2(CO)9
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The complex 2,3-bis(carbomethoxy)-9,10-dichlorobicyclo-deca-2,5-diene-η4(2,5)-tricarbonyliron (II) has been synthesized by the reaction of 2,3-bi(carbomethoxy)-9,10-dichlorobicyclo-deca-2,5-diene (I) with Fe2(CO)9.The complex has been characterized by IR, PMR, mass spectra and elemental analyses.
- Ullah, S. S.,Kabir, S. E.,Molla, M. E.,Karim, M.
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p. 404 - 405
(2007/10/02)
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- REACTIONS INVOLVING TRANSITION METALS. XIX. SOME REACTIONS OF PERFLUORONORBORNADIENE WITH LOW VALENT TRANSITION METAL COMPLEXES
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Perfluoronorbornadiene reacts with the compounds to give the adducts and in which one of the double bonds is coordinated to the metal atom.The platinum complex reacts further with to give 2> having both double bonds coordinated to a Pt atom.The carbonylmetal anions -> react to form the mono-substitution products (M = Mn(CO)5, Re(CO)5, Ir(CO)2(PPh3)2, Rh(CO)2(PPh3)2, but the use of an excess of - leads to substitution of one fluorine atom on each of the double bonds.The complex having M = Mn(CO)5 reacts with to afford the derivative >, and the compound where M = Ir(CO)2(PPh3)2 undergoes an oxidative addition reaction with acetyl chloride.Oxidative coupling products have been isolated on UV irradiation of a mixture of perfluoronorbornadiene and 4-CH2=CRCH=CH2)(CO)3> (R = H, Me), and under similar conditions the reaction with Fe(CO)5 affords in very low yield.
- Booth, Brian L.,Casey, Sylvia,Haszeldine, Robert N.
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p. 289 - 300
(2007/10/02)
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- REACTIONS INVOLVING TRANSITION METALS. XX. A COMPARISON OF THE REACTIONS OF 1,2,3,4,7,7-HEXAFLUOROBICYCLOHEPTADIENE, AND 2,3-BIS(TRIMETHYLTIN)- AND 2,3-DICHLORO-1,4,5,6,7,7-HEXAFLUOROBICYCLOHEPTA-2,5-DIENES WITH LOW VALENT TRANSITION METAL COMPLEXES
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1,2,3,4,7,7-hexafluorobicycloheptadiene (1) and 2,3-bis(trimethyltin)-1,4,5,6,7,7-hexafluorobicyclohepta-2,5-diene (2) react with (M = Pt, Pd) to afford air-stable adducts. 2,3-Dichloro-1,4,5,6,7,7-hexafluorobicyclohepta-2,5-diene (3) gives only with , but a low yield of an adduct was obtained with .The diene 1 also reacts with Fe(CO)5 to form the complex , and with to give in which the diene acts as a bidentate ligand.Similar products could not be isolated from the reactions of 2 and 3.A stable adduct, believed to be Rh(CO)2(μ-Cl)2Rh(CO)2> has been isolated from the reaction between 2 and 2.This adduct reacts with PPh3 to give the bridge-cleavage product RhCl(CO)(PPh3)2>.Reaction of 1 with 2 gives an unstable adduct which could not be isolated, and 2 does not react at room temperature.The chloro derivative 3 reacts with to give the adduct , but 1 and 2 do not react under similar conditions.Stable substitution products (R = H, M = Fe(CO)2(η-C5H5); R = SnMe3, M = Fe(CO)2(η-C5H5), Mn(CO)5, Ir(CO)2(PPh3)2, Rh(CO)2(PPh3)2; R = Cl, M = Ir(CO)2(PPh3)2, Rh(CO)2(PPh3)2) have been isolated from the reactions of the dienes with carbonylmetal anions.Insertion of the CH=CH bond occurs when 1 is heated with to give and this, on reaction with either PPh3 or , gives .
- Booth, Brian L.,Casey, Sylvia,Critchley, Robert P.,Haszeldine, Robert N.
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p. 301 - 312
(2007/10/02)
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- Fluxionality in (cyclohtptatriene)iron tricarbonyl complexes
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1H NMR spin saturation transfer experiments were undertaken to measure the barrier for 1,3 iron shifts in (cyclobeptatriene)iron tricarbonyl (CHT = cycloheptatriene) complexes.
- Karel, Karin J.
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p. 419 - 430
(2008/10/08)
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