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Protonation of Fischer-type alkylidyne carbonyltungsten complexes. Structural comparison of alkylidyne and alkylidene metal complexes, including a neutron diffraction study of [W(CHCH3)Cl2(CO)(PMe3)2]

1998; Elsevier BV; Volume: 279; Issue: 1 Linguagem: Inglês

10.1016/s0020-1693(98)00004-8

1873-3255

Cecilia M. Bastos, Ken S. Lee, Michael A. Kjelsberg, Andreas Mayr, Donna Van Engen, Stephen A. Koch, John D. Franolic, Wim T. Klooster, Thomas F. Koetzle,

Synthesis and characterization of novel inorganic/organometallic compounds

Protonation of alkylidyne tungsten complexes of the types [W(CR)Cl(CO)(PMe3)3] or [W(CR)Cl(CO)(py)(PMe3)2] with HCl affords the η2-alkylidene tungsten complexes [W(CHR)Cl2(CO)(PMe3)2] (7) (R = Me, Et, Ph, p-Tol). Protonation of the complexes [W(CR)X(CO)(CNR′)(PMe3)2] with HOSO2CF3 or HBF4 gives the alkylidene complexes [W(CHR)X(CO)(CNR′)(PMe3)2][Y] (8) (R = Me, R′ = CMe3, X = Cl, Y = CF3SO3, R = Ph, X = Cl; R′ = CMe3, Y = CF3SO3, BF4; R′ = C6H11, Y = BF4; R′ = C6H3Me2-2,6, Y = CF3SO3, R = Ph, R′ = CMe3, X = I, Y = CF3SO3, BF4). The CH bonds of the alkylidene ligands are easily deprotonated with bases such as pyrrolidinocyclopentene or triethylamine. The solid state structures of [W(CPh)Cl(CO)(CNCMe3)(PMe3)2] (5b), [W(CHMe)Cl2(CO)(PMe3)2] (7a). [W(CHPh)Cl2(CO)(PMe3)2] (7c), and [W(CHPh)Cl(CO)(CNCMe3)(PMe3)2][BF4] (8c) were determined by X-ray crystallography. The structure of 7a was also determined by neutron diffraction. Based on the neutron diffraction data of 7a, and closely matching results from the X-ray diffraction studies, it is found that the η2-coordination mode of the alkylidene ligands gives rise to almost equal WC(R) and WH bond distances, 1.857(4) and 1.922(6) Å, respectively, in the case of 7a. The length of the alkylidene CH bond in 7a is 1.185(7) Å. The structural comparison of 5b and 8c reveals that the protonation of the alkylidyne ligand causes the WCPh bond to lengthen by less than 0.1 Å and the WCPh angle to bend by about 15°. The major induced structural change, however, may be described as a lateral shift of the CPh group by about 0.6 Å away from the coordination axis defined by the extension of the ClW vector.