(Phenylthiomethyl)silanes and (butyltelluromethyl)silanes as novel bifunctional ligands for the construction of dithioether-, ditelluroether- and transition metal-silicon complexes

The functionalized silanes (PhSCH2)(2)SiPh2 (1a), (PhSCH2)(2)Si(vinyl)Me (1b), (PhSCH2)(2)Si(H)Me (1c) and (PhSCH2)(3)SiH (1d) have been prepared and co-ordinated as chelating dithioether ligands or via a covalent M-Si bond to various transition metal centers. Thus. reaction of 1a with [PtCl2(PhCN)(2)] affords the dithioether complex cis-[PtCl2{(PhSCH2)(2)SiPh2}] (3), which exist in solution as mixtures of DL- and meso-invertomers. Treatment of [Re(p-Br)(CO)(3)THF](2) with 1a-c yielded the stereochemically rigid chelate complexes fac-[ReBr(CO)(3){(PhSCH2)(2)(SiRR2)-R-1}] (R-1, R-2 = Ph (4a)), (R-1 = vinyl, R-2 = Me (4b)), (R-1 = H, R-2 = Me (4c)). Due to the presence of two different substituents R-1 and R-2 on Si, 4b and 4c are isolated as 50:50 mixtures of diastereomers. The presence of a Si-H function in 1c.d can be exploited for Si-H activation reactions. Thus, oxidative addition on [Pt(PPh3)(2)(CH2=CH2)] yields the fluxional hydrido silyl complex [Pt(H)(PPh3)(2){Si(CH2Ph)(2)Me}] (5a) and the rigid derivative [Pt(H)(PPh3)(2){Si(CH2SPh)(3)}] (5b). The ditelluroether complexes cis-[PtCl2{(RTeCH2)(2)SiMe2)] (6a, R = Ph), (6b, R = n-Bu) are obtained by treatment of [PtCl2(PhCN)(2)] with (PhTeCH2)(2)SiMe2 (2a) and (n-BuTeCH2)(2)SiMe2 (2b), respectively. The complex fac-[ReBr(CO)(3){n-BuTeCH2)(2)SiMe2}] (7) results from the reaction of [Re(mu-Br)(Co)(3)THF](2) with (2b). The new compounds have been studied by multinuclear NMR techniques, the crystal structures of 3, 4a, 5 and 6b have been determined by X-ray diffraction studies. (C) 2002 Elsevier Science B.V. All rights reserved.