Tertiary phosphine induced migratory carbonyl insertion in cyclopentadienyl complexes of iron(II)

Cyclopentadienyldicarbonylmethyliron, [CpFe(CO)₂Me] (1), undergoes migratory carbonyl insertion under the influence of isosteric phosphine ligands P(4-FC₆H₄)₃ and P(4-MeC₆H₄)₃. The products of the reaction, [CpFe(CO)(COMe)P(4-FC₆H₄)₃] (2a) and [CpFe(CO)(COMe)P(4-MeC₆H₄)₃] (2b), were characterised by X-ray crystallography. In both structures, the iron atom adopts a pseudo octahedral coordination geometry. Fe-P bond distances are the same at 2.1932(8) Å in 2a and 2b, respectively. Thus, contrary to what was expected, X-ray data could not be used to quantitatively differentiate between the two phosphine ligands in 2a and 2b. Therefore, additional spectroscopic techniques such as IR and NMR were employed. Similarly, the Fe-C bond lengths of the carbonyl (Fe-CO) and acetyl (Fe-COMe) are 1.748(3) and 1.955(3) in 2a, and 1.744(3) and 1.951(3) Å in 2b, respectively.The migratory carbonyl insertion was studied by NMR, IR, and UV-vis spectroscopies to determine the mechanism and the rate law. Results from NMR spectroscopy show that the formation of the product is accompanied by oxidation of the corresponding phosphine ligand. An increase in the reactivity of migratory carbonyl insertion for P(4-MeC₆H₄)₃ was observed when the solvent was changed from CH₂Cl₂ to MeCN. The kinetic data showed that P(4-MeC₆H₄)₃ reacts faster than P(4-FC₆H₄)₃.     

Platinum and rhenium phosphine carbonyl thiolate complexes

The heterometallic complex (CO)₃(PPh₃)Re(μ-SPr)Pt(PPh₃)(CO) (I) was formed in the reaction of Re₂(μ-SPr)₂(CO)₈ with (PPh₃)₂Pt(C₂Ph₂), together with (CO)₃(PPh₃)Re(μ-SPr)₂Re(CO)₄ (II), which was also prepared by an alternative synthesis. Compounds I and II were characterized by X-ray diffraction. In I, the Re-Pt single bond, 2.7414(5) Å, is supplemented by a thiolate bridge with shortened bonds: Pt-S (2.336(2) Å) and Re-S (2.449(2) Å). The Re-P (2.469(2) Å) and Pt-P (2.329(2) Å) bonds are also shortened. Complex II resulting from replacement of one CO group in the starting rhenium complex by triphenylphosphine has no M-M bond, and the Re-S and Re-P bond lengths (2.511(2)–2.527(2) and 2.517(3) Å) are close to the length of single bonds. It is assumed that the platinum atom in I is attached to the formally double bond Re ? SPr arising upon dissociation of Re₂(μ-SPr)₂(CO)₈.     

Tertiary arsine-stabilised arsenium salts: syntheses and comparisons with phosphine analogues

The first tertiary arsine-stabilised arsenium salts, [(L)AsMePh]OTf (L = Ph3As, Me2PhAs, [2-(MeOCH2)C6H4]Ph2As, [2-(MeOCH2)C6H4]Me2As), have been prepared by chloride abstraction from chloromethylphenylarsine with trimethylsilyl triflate in the presence of the arsine. The complexes have been characterised by crystallography and 1H NMR spectroscopy. The chiral cations in the complexes have structures based on the trigonal pyramid in which the arsine is coordinated orthogonally to the prochiral, six-electron MePhAs+ ion that forms the base of the pyramid. The NMR data for the complexes in dichloromethane-d2 are consistent with rapid exchange of the arsine on the arsenium ion, even at 183 K. The corresponding phosphine-stabilised complexes are considerably more stable than their arsine counterparts in dichloromethane-d2 with the free energy of activation DeltaG = ca. 60 kJ mol(-1) being calculated for phosphine exchange in [(Me2PhP)AsMePh]OTf at 281 K; for [(Me2[2-(MeOCH2)C6H4]P)AsMePh]OTf in the same solvent, DeltaG = ca. 70 kJ mol(-1) at 323 K.     

Tertiary phosphine complexes of rhenium: A spectroscopic study

Complexes of the type ReOX₃L₂, ReNX₂L₃, ReX₃(NO)L₂ and ReX₂(NO)L₃ have been studied using, UV visible, IR and H¹, C¹³ NMR spectroscopy. (X is a halogen, Cl, Br, I and L is a tertiary phosphine Et₃P and Et₂PhP). Evidence obtained on the blue cis isomer ReOCl₃L₂ suggests that the halogens are arranged on a face of the octahedral complex. Assignments of v(Re-X) and v(Re-P) vibrations have been made. Three complexes of technetium, [TcCl₄(Ph₃P)₂], [TcCl₃(Et₂PhP)₃] and [TcCl₃(NO)(Et₂PhP)₂] have been isolated.     

Nature of the complexes formed by alkali metal halides with phosphine oxides

Reaction of alkali metal halides (MX) with methylenediphosphine oxides and various related compounds in nonaqueous solutions leads to the formation of complex compounds. The compositions, properties, and stabilities of these compounds, which have been studied in detail in acetonitrile, are determined by the nature of the cations and anions of the alkali metal halides. Formation of neutral complexes with the composition [MX · L] and cationic complexes with the composition [ML]⁺ has been established. The most characteristic representative of complexes of the first type is [NaI · L]; in the complexes studied, L=R₂P(O)CH₂P(O)R₂ (R=Bu, BuO, or Ph), Ph₂P(O)CH₂P(O) (OC₂H₅)CH₂P(O)Ph₂ and (p-OCH₃C₆H₄)₂P(O)CH₂P(O)(C₆H₄CF₃-p)₂. Compound [LiL]⁺ is characteristic of complexes of the second type; the compounds containing Ph₃P(O), Ph₂P(O)CH₂P(O)Ph₂, and Ph₂P(O)CH₂P(O)(OC₂H₅)CH₂P(O)Ph₂ as ligands have been studied. Stability constants of the complexes [NaI · L] and [LiL]⁺ have been determined by measuring the dependence of the electrical conductivity of solutions of the alkali metal halides in acetonitrile on the concentration of the ligands. The complex-forming power of phosphine oxides increases with increase in the number of P=O groups. Stabilities of the complexes [NaI · L] with ligands with identical structure decrease with increase in the electronegativity of the substituents on the phosphorus atoms.     

Interaction of cyclopentadienyl carbonyl phosphine complexes of manganese with Lewis acids. Infrared Spectra*

From IR-spectroscopic studies it is shown that phosphine derivatives of cyclopentadienylmanganese tricarbonyl interact reversibly with SnCl₄ and another Lewis acids in CH₂Cl₂ solution. The structures of the resulting complexes are discussed. Complex formation is favoured as the electron-donor properties of both the π-ring substituents and of the phosphine ligands attached to manganese atom are increased. The ability of Lewis acids to undergo such complex formation follows the series: SnCl₄ > SbCl₃ > HgCl₂ > GeCl₄.     

Basicity of metal carbonyl complexes. No. 20. Protonation of cymmantrene derivatives containing two phosphine ligands

Conclusions ⁵-RC₅H₄Mn(CO)(P)₂ complexes, where (P)₂ is a bidentate phosphine, or (P) is Ph₂PMe or (EtO)₃P, are organometailic Lewis bases, and undergo protonation at the Mn atom in the presence of CF₃COOH. The protonated forms display square pyramidal configurations and exist in the form of cis- and trans-isomers, depending on the nature of the phosphine ligand and the protonation conditions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1388–1392, June, 1987.For Communication No. 19, see [1].     

Facile syntheses of silylene nickel carbonyl complexes from Lewis base stabilized chlorosilylenes

Two silylene nickel carbonyl complexes of composition L·Ni(CO)(3) (1) {L = PhC(NtBu)(2)SiCl} and L'(2)·Ni(CO)(2) (2) { L' = RSiCl(2), R = (1,3-bis-(2,6-diisopropylphenyl)imidazol-2-ylidene)} were prepared by reacting 1 equivalent of Ni(CO)(4) with 1 equivalent of heteroleptic chlorosilylene L for 1 and with 2 equivalents of carbene stabilized dichlorosilylene L' for 2 in toluene at room temperature. Both complexes 1 and 2 were characterized by single-crystal X-ray analysis, NMR and IR spectroscopy, EI-MS spectrometry, and elemental analysis.     

Rhodium(I) carbonyl complexes of ether‐phosphine ligands and their reactivity

The reactions of dimeric complex [Rh(CO)₂Cl]₂ with hemilabile ether‐phosphine ligands Ph₂P(CH₂) _nOR [n = 1, R = CH₃ (a); n = 2, R = C₂H₅ (b)] yield cis‐[Rh(CO)₂Cl(P ～ O)] (1) [P ～ O = η ¹‐(P) coordinated]. Halide abstraction reactions of 1 with AgClO₄ produce cis‐[Rh(CO)₂(P ∩ O)]ClO₄ (2) [P ∩ O = η ²‐(P,O)chelated]. Oxidative addition reactions of 1 with CH₃I and I₂ give rhodium(III) complexes [Rh(CO)(COCH₃)ClI(P ∩ O)] (3) and [Rh(CO)ClI₂(P ∩ O)] (4) respectively. The complexes have been characterized by elemental analyses, IR, ¹H, ¹³C and ³¹P NMR spectroscopy. The catalytic activity of 1 for carbonylation of methanol is higher than that of the well‐known [Rh(CO)₂I₂]^? species. Copyright © 2002 John Wiley & Sons, Ltd.     

Mixed schiff base,carbonyl(phosphine)rhenium(I) complexes

Summary The Re(CO)₂(L)P₂ complexes (L=N-methylsalicylideneiminate,N-phenylsalicylideneiminate, halfN,N-ethylenebis(salicylideneiminate) or 8-hydroxyquinolinate; P=dimethyl(phenyl)phosphine or triphenylphosphine) were synthesized from the ReCl(CO)₃P₂ complexes and characterized by elemental analysis, i.r. and¹H n.m.r. spectroscopy.     

Substituted metal carbonyls: I. Molybdenum carbonyl complexes containing unidentate and bridging diphosphines: One-pot syntheses

Trimethylamine N-oxide (TMNO)-initiated decarbonylations of Mo(CO)₆ followed by phosphine additions yield the complexes Mo(CO)₅(Ph₂PCH₂PPh₂), which consists of a unidentate diphosphine, and the dinuclear phosphine-bridged complexes Mo₂(CO)₁₀(μ-Ph₂P(CH₂)_nPPh₂) (where n = 2, 3) at ambient temperatures. The IR and NMR (¹H and ³¹P) spectroscopic and structural properties of these complexes are presented and discussed. Some thermal analytical data are summarised.     

Far infrared spectroscopy of complexes of copper(I) halides with phosphine and amine ligands

Far i.r. spectra are reported for 34 adducts of phosphine and amine bases with copper (I) halides in which the copper atom is coordinated to only one terminal halide. CuX stretching frequencies are assigned for all of the chloro complexes and for most of the bromo and iodo complexes. The CuX stretching frequencies have been found to depend primarily on the CuX̵ bond length, and appear to be relatively independent of the nature of the coordinating ligands. Best fit curves to the experimental data correspond to a dependence of ν(CuX) on the inverse nth power of r(CuX), where n is approximately equal to 5. Metal—halogen bond stretching force constants have been calculated for copper(I) and related silver(I) and gold(I) halide complexes assuming that the MX entity behaves as an uncoupled diatomic molecule. The results show that for three-coordinate copper(I) the force constants decrease in the order CuCl>CuBr>CuI and that the same trend is shown for four-coordinate copper(I) complexes, but the differences are considerably smaller than for the three-coordinate case. Analogous trends are found for the two- and three-coordinate gold compounds.     

Pd(I) phosphine carbonyl and hydride complexes implicated in the palladium-catalyzed oxo process

Reduction of compound "Pd(bcope)(OTf)2" [bcope = (c-C8H14-1,5)PCH2CH2P(c-C8H14-1,5); OTf = O3SCF3] with H2/CO yields a mixture of Pd(I) compounds [Pd2(bcope)2(CO)2](OTf)2 (1) and [Pd2(bcope)2(mu-CO)(mu-H)](OTf) (2), whereas reduction with H2 or Ph3SiH in the absence of CO leads to [Pd3(bcope)3(mu3-H)2](OTf)2 (3). Exposure of 3 to CO leads to 1 and 2. The structures of 1 and 3 have been determined by X-ray diffraction. Complex [Pd2(bcope)2(CO)2](2+) displays a metal-metal bonded structure with a square planar environment for the Pd atoms and terminally bonded CO ligands and is fluxional in solution. DFT calculations aid the interpretation of this fluxional behavior as resulting from an intramolecular exchange of the two inequivalent P atom positions via a symmetric bis-CO-bridged intermediate. A cyclic voltammetric investigation reveals a very complex redox behavior for the "Pd(bcope)(OTf)2"/CO system and suggests possible pathways leading to the formation of the various observed products, as well as their relationship with the active species of the PdL2(2+)/CO/H2-catalyzed oxo processes (L2 = diphosphine ligands).     

Stereoselective syntheses of solenopsin A and B

Effective and convenient syntheses of solenopsin A and B have been developed which involve the Beckman rearrangement-alkylation reaction promoted by organoaluminum reagents and a new stereoselective reduction of imino functional group.     

Synthetic and structural studies of tolyl-dithiolate diiron carbonyl complexes with tris(aryl)phosphine co-ligands

Reaction of [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₆ (1) with 2 equivalents of PPh₃ gave the monosubstituted complex [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₅(PPh₃) (2) plus the disubstituted [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₄(PPh₃)₂ (3), while the complexes [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₅[P(3-C₆H₄CH₃)₃] (4) and [μ-SC₆H₃(CH₃)S-μ]Fe₂(CO)₅[P(4-C₆H₄F)₃] (5) were prepared by the reactions of 1 with P(3-C₆H₄CH₃)₃ or P(4-C₆H₄F)₃ in the presence of Me₃NO. Complexes 3–5 were characterized by IR, NMR spectroscopy and single-crystal X-ray diffraction analysis. The molecular structures of 3–5 reveal that in each case, the phosphine ligand occupies the apical position in an overall distorted square pyramidal iron(I) complex geometry.     

Pentamethylcyclopentadienyl niobium(III) nitrene complexes containing phosphine,carbonyl, olefin and acetylene ligands

The novel d² niobium nitrene complex (η-C₅Me₅)Nb(NAr)(PMe₃)₂ (Ar=2,6-ⁱPr₂C₆H₃) (1) is accessible via     

Promotion of acetophenone formation from methyl(phenyl)rhodium carbonyl complexes by organic halides

[C₅Me₅RhPh(CO)CH₃] reacted thermally to give acetophenone (27%) and toluene (9%); acetophenone formation was substantially increased in the presence of halobenzenes PhX (the order of effectiveness being X = I> Br> Cl) or methyl iodide, but 1-electron oxidisers promoted C---C coupling (toluene formation).