Esr spectral determination of the relative rate constants for the abstraction of halogen by M(CO)4L species (L=CO,PPh3; M=Cr,Mo, W)

Conclusion The rate constants for the abstraction of bromine from PhCH₂Br and of chlorine from CCl₄ by M(CO)₅ and M(CO)₄PPh₃ species (M=Cr, Mo, and W) are two orders of magnitude greater than the rate constants for chlorine abstraction from PhCH₂Cl; the difference in the rates of chlorine abstraction from CCl₄ and C₂Cl₆ by these species is within an order of magnitude.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1149–1151, May, 1987.     

A new method of preparation of the anionic decacarbonyls M2(CO)102− (M = Cr,Mo, W) and syntheses and properties of Mg(THF)2[M2(CO)10]

The anionic decacarbonyIs M₂(CO)₁₀^2? were synthesized via reduction reactions of CrCl₃, MoCl₅ and WCl₆ with metallic magnesium or sodium amalgam under carbon monoxide. Chemical properties and IR characteristics of the magnesium salt Mg(THF)₂[M₂(CO)₁₀] are desribed.     

Photochemical reactions of M(CO)6 (M = Cr,Mo, W) with Ph2P(S)P(S)Ph2

New complexes {M(CO)₄[Ph₂P(S)P(S)Ph₂]} (M = Cr, Mo and W), (1a)–(3a), [(1a), M = Cr; (2a), M = Mo; (3a), M = W] and {M₂(CO)₁₀[-Ph₂P(S)P(S)Ph₂]} (M = Cr, Mo, W), [(1b)–(3b) [(1b), M = Cr; (2b), M = Mo; (3b), M = W]] have been prepared by the photochemical reaction of M(CO)₆ with Ph₂P(S)P(S)Ph₂ and characterized by elemental analyses, f.t.-i.r. and ³¹P-(¹H)-n.m.r. spectroscopy and by FAB-mass spectrometry. The spectra suggest cis-chelate bidentate coordination of the ligand in {M(CO)₄[Ph₂P(S)P(S)Ph₂]} and cis-bridging bidentate coordination of the ligand between two metals in (M = Cr, Mo and W).     

Metal germylyne complexes [Mtbd1;Ge-R] and metallogermylenes [M-Ge-R]: DFT analysis of the systems [(Cp)(CO)(n)()Mtbd1;GeMe] (M = Cr,Mo, W,Fe(2+), n = 2; M = Fe,n = 1) and [(Cp)(CO)(n)()M-GeMe] (M = Cr,Mo, W,n = 3; M = Fe,n = 2)

Quantum chemical calculations at the gradient corrected DFT level using the exchange correlation functionals BP86 and B3LYP of the geometries of the title compounds are reported. The theoretically predicted bond lengths and angles of the model compounds are in excellent agreement with experiment. The nature of the metal-ligand interactions is quantitatively analyzed with an energy decomposition method. The analysis of the electronic structure of the neutral metal germylyne complexes Ia-Id and the metallogermylenes IIa-IId shows that the former compounds have about the same degree of electrostatic and covalent bonding, while the relative strength of the covalent contributions in the latter molecules is lower (41-42%) than the electrostatic attraction (58-59%). The a' '(pi) bonding contribution in the group-6 germylyne complexes Ia-Ic is rather high (42% of the orbital interactions). In the iron complex Id, it is even higher (53.8%) than the sigma bonding. The pi bonding contributions to the covalent bonding become much less (18-20%) in the metallogermylenes IIa-IId.     

Linear versus bent bonding in metal-phosphinidene complexes: Theoretical studies of the electrophilic phosphinidene complexes [(Cp)(CO)2MPMe)], [(Cp)(CO)3MPMe)] (M = Cr, Mo, W)

Density functional theory calculations have been performed for the title phosphinidene complexes using the exchange correlation functionals BP86 and B3LYP. The optimized bond lengths and angles of the model compounds are in excellent agreement with experiment. The M-P bond lengths in linear phosphinidene complexes correspond to a Pauling bond order of ∼ 3. The bent geometries at phosphorus in the bent metal phosphinidene complexes are consistent with the presence of a trivalent phosphorus(III) center which is singly bonded to carbon and doubly bonded to transition metal. The analysis of the delocalized Kohn-Sham orbitals shows the polarization of the M-P σ bonding orbitals towards the phosphorus atom in the MPMe bonds, while in the MPMe bond, the contributions of metal and phosphorus are almost the same. In the linear phosphinidene complexes the contributions of the covalent bonding ΔE_orb are more than the electrostatic interaction ΔE_elstat. The bent phosphinidene complexes have a lower degree of covalent bonding than the linear phosphinidene complexes. The major differences between the linear and bent phosphinidene complexes are found in the degree of π-bonding. The MPMe bonds show a true M-P π bond and a deviated π bond due to slight bent M-P-C bond angles. The MPMe bonds show a true M-P π bond and a lone-pair on phosphorus.     

Si(SiMe3)3]3Ge9M(CO)3(-) (M=Cr, Mo, W): coordination chemistry with metalloid clusters

Very recently it was shown that the metalloid cluster compound {Ge(9)[Si(SiMe(3))(3)](3)}(-)1 can be used for subsequent reactions as the shielding of the cluster core is rather incomplete. So the reaction of 1 with Cr(CO)(3)(CH(3)CN)(3) leads to a cluster enlargement where the chromium atom is incorporated into the cluster core. Here further applications of 1 as a flexible ligand in coordination chemistry are presented where the reaction of 1 with Mo(CO)(3)(EtCN)(3) and W(CO)(3)(CH(3)CN)(3) leads to [(CO)(3)MoGe(9)R(3)](-)4 and [(CO)(3)WGe(9)R(3)](-)5 respectively (R = Si(SiMe(3))(3)), showing that 1 can indeed be used as a flexible ligand in coordination chemistry. Structural and electronic properties of the Ge(9)M clusters 4 and 5 are discussed as well as mechanistic aspects of their formation.     

Direct Electrochemical Investigations of 17-Electron Complexes of CpM(CO)(3)(*) (M = Mo, W, and Cr)

Photolysis of complexes of the type M(2)(CO)(6)(RC(5)H(4))(2) (where M = W, Mo, Cr and R = H (Cp) or CH(3) (Cp')) leads to the production of short lived 17-electron radicals. Direct electrochemical characterization of these intermediates has been achieved using a technique known as photomodulated voltammetry (PMV). The results from PMV analysis are in excellent agreement with literature estimates for CpMo(CO)(3)(*) and CpCr(CO)(3)(*). However, CpW(CO)(3)(*) is found to be shifted oxidatively 115 mV relative to previous literature estimates. The change in the value for the tungsten complex changes previous estimates to the bond dissociation energy for tungsten metal hydrides by 3.0 +/- 0.9 kcal/mol. Lifetime information on the radicals is also reported based on the phase shift of the electrochemical signal observed by PMV under limiting current conditions.     

紫外激光诱导C60与M(CO)6(M=Cr,Mo, W)的配位反应

研究了用紫外激光(355 nm)诱导C_(60)与金属羰基化合物M(CO)_6(M＝Cr；Mo，W)的配位反应，合成了具有C_(4υ)对称性的配位络合物(η~2－C_(60))M(CO)_5，并初步讨论了C_(60)与M(CO)_6反应的动力学过程．     

Photochemical reactions of metal carbonyls [M(CO)6 (M = Cr,Mo and W), Re(CO)5Br,Mn(CO)3Cp] with 2-hydroxyacetophenone methanesulfonylhydrazone (apmsh)

Five new complexes, [M(CO)₅(apmsh)] [M = Cr; (1), Mo; (2), W; (3)], [Re(CO)₄Br(apmsh)] (4) and [Mn(CO)₃(apmsh)] (5) have been synthesized by the photochemical reaction of metal carbonyls [M(CO)₆] (M = Cr, Mo and W), [Re(CO)₅Br], and [Mn(CO)₃Cp] with 2-hydroxyacetophenone methanesulfonylhydrazone (apmsh). The complexes have been characterized by elemental analysis, mass spectrometry, f.t.-i.r. and ¹H spectroscopy. Spectroscopic studies show that apmsh behaves as a monodentate ligand coordinating via the imine N donor atom in [M(CO)₅(apmsh)] (1–4) and as a tridentate ligand in (5).     

Syntheses and molecular structures of eta3-[(eta5-Cp*)(CO)2Fe-AsPC(SiMe3)2]M(CO)2(eta5-Cp)(M = Mo, W): the first complexes featuring eta3-arsaphosphaallyl ligands

Reaction of (eta5-Cp)(CO)2M=P=C(SiMe3)2 4a (M = Mo) and 4b (M = W) with (eta5-Cp*)(CO)2Fe-As=C(NMe2)2 5 affords the eta3-1-arsa-2-phosphaallyl complexes [(eta5-Cp*)(CO)2Fe-AsPC(SiMe3)2]M(CO)2(eta5-Cp) 6a and 6b, the molecular structures of which were determined by X-ray analyses.     

Synthesis of the new, cubane-like W3S4Co cluster core. Completion of the homologous series [(eta5-Cp')3M3S4Co(CO)] (M = Cr, Mo, W)

Reaction between the cluster salts [(eta(5)-Cp')(3)M(3)S(4)][pts] (M = Mo, W; Cp' = methylcyclopentadienyl; pts = p-toluenesulfonate) and [Co(2)(CO)(8)] yielded the electroneutral clusters [(eta(5)-Cp')(3)M(3)S(4)Co(CO)]. The molecular structure of [(eta(5)-Cp')(3)W(3)S(4)Co(CO)] was determined by single-crystal X-ray diffraction methods. The unprecedented 60 electron W(3)S(4)Co cluster completes a homologous series of heterobimetallic clusters, [(eta(5)-Cp')(3)M(3)S(4)Co(CO)] (M = Cr, Mo, W), containing a cubane-like core motif.     

Darstellung und Eigenschaften von Komplexen des Typs cis-(RCN)3M(CO)3 (M = Cr,M, W)

Metal complexes of the type cis-(RCN)₃M(CO)₃ (M = Cr, Mo, W) have been prepared by different methods starting with M(CO)₆ or, more conveniently, with substituted derivatives of the metal hexacarbonyls. Infrared spectroscopic studies indicate that the strength of the nitrile-to-metal bond in cis-(RCN)₃M(CO)₃ is only sligthly influenced by the R group. The chromium compounds cis-(RCN)₃Cr(CO)₃ may be used as starting materials for the preparation of hexaalkylborazine-chromium-tricarbonyls.     

Synthesis of the New Silanediyldiphosphinite tBu2Si(OPPh2)2 and its Reactions with the Norbornadiene Complexes C7H8M(CO)4 (M = Cr,Mo, W). Crystal Structures of cis-M(CO)4[tBu2Si(OPPh2)2] (M = Cr,Mo)

Silanediyldiphosphinite tBu₂Si(OPPh₂)₂ 1 has been synthesised. 1 reacts with the norbornadiene complexes C₇H₈M(CO)₄ (M = Cr, Mo, W) to give six-membered chelate rings of the type cis-M(CO)₄[tBu₂Si(OPPh₂)₂] 2–4 . The crystal structures of the chromium and molybdenum complexes cis-Cr(CO)₄[tBu₂Si(OPPh₂)₂] 2 and cis-Mo(CO)₄[tBu₂Si(OPPh₂)₂] 3 have been determined. Both complexes crystallise in the triclinic system (space group P1 ) with unit cell parameters: ( 2 ) a = 1 093(3) pm, b = 1 477(5) pm and c = 1 542(5) pm; α = 108.4(2)°, b? = 103.87(11)° and b? = 104.57(10)°; U = 2.143(12) nm³; Z = 2; ( 3 ) a = 1 097.8(2) pm, b = 1 483.7(2) pm and c = 1 554.3(2) pm; α = 108.10(1)°, b? = 103.956(6)° and γ = 104.213(7)°; U = 2.1899(6) nm³; Z = 2. Both 2 and 3 consist of discrete, slightly distorted, octahedral monomers in which the six-membered chelate rings are essentially planar. In contrast, the conformations of the chelate rings found in crystal structures of analogous complexes vary from twist-boat to “chaise longue”.     

金属羰基化合物M(CO)6(M=Cr,Mo, W)氧原子转移反应动力学与机理

本文研究了PPh3存在与不存在的情况下, M(CO)6(M=Cr, Mo, W)与三甲胺氧化物me3NO在CH2Cl2中的氧原子转移反应动力学. 反应速率遵循: r=k[M(CO)6][Me3NO], 并且rW>rMo>rCr, 并根据实验结果提出了反应机理, 讨论了溶剂对反应速率的影响.     

Reactions of the carbonyl complexes M(CO)3(L)3 (L = py,M = Mo,W; L = NH3, M = Mo) and M(CO)4(2-Mepy)2 (M = Mo,W) with HgX2 (X = Cl,CN, SCN)

The reactions of the substituted Group VI metal carbonyls of the type M(CO)₄(2-Mepy)₂ (M = Mo, w) and M(CO)₃(L)₃ (L = py, M = Mo, W; L = NH₃, M = Mo) with mercuric derivatives HgX₂ (X = Cl, CN, SCN) have given rise to three series of tricarbonyl complexes: M(CO)₃(py)HgCl₂ · 1/2HgCl₂ (M = Mo, W); 2[M(CO)₃(L)]Hg(CN)·nHg(CN)_x (L = py, M = Mo, W, n = $\text{1}\text{2}$, × = 2; L = 2- Mepy, × = 1; M = Mo, n = 3; M = W, n = 1); and [M(CO)₃(L)Hg(SCN)₂ · nHg(SCN)₂] (L = py, M = Mo,W, n = 0; L = 2-Mepy, M = Mo, W, n = $\text{1}\text{2}$; L = NH₃, M = Mo, n = 0) depending on which mercuric compound is employed. All the reactions with Hg(SCN)₂ give isolable products whereas those with Hg(CN)₂ and HgCl₂ did so far only the reactions with [M(CO)₄(2-Mepy)₂] and M(CO)₃(py)₃. The greater reactivity of Hg(SCN)₂ than of Hg(CN)₂ and HgCl₂ is consistent with the various acceptor capacities of the groups bonded to the mercury atom.The reactions studied always involve displacement of the N-donor ligand of the original complex and partial or total displacement of the halide or pseudohalide groups of the mercury compound to give in all cases compounds containing MHg bonds. In addition, elimination of a CO group in the tetracarbonyl complexes M(CO)₄(2-Mepy)₂occurs.     

钼(钨)/铜/硫三核簇合物[A]2[MS4(CuCN)2] (M=Mo,W;A=Et4N,PPh4)的合成及晶体结构

合成了四个三核簇合物[A]2[MS4(CuCN)2](1A＝Et4N,M＝Mo;2A＝PPh4,M＝W;3A＝Et4N,M＝W;4A＝PPh4,M＝Mo),测定了[Et4N]2[MoS4(CuCN)2]*H2O(1*H2O)和[PPh4]2[WS4(CuCN)2]*0.5DMF*H2O(2*0.5DMF*H2O)的晶体结构.1和2的簇阴离子[MS4(CuCN)2]2-(M＝Mo,W)均具有一个双齿配体MS42-和两个CuCN形成的近似D2d对称性结构.