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

The functionalized silanes (PhSCH2)2SiPh2 (1a), (PhSCH2)2Si(vinyl)Me (1b), (PhSCH2)2Si(H)Me (1c) and (PhSCH2)3SiH (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)2SiPh2}] (3), which exist in solution as mixtures of dl- and meso-invertomers. Treatment of [Re(μ-Br)(CO)3THF]2 with 1a–c yielded the stereochemically rigid chelate complexes fac-[ReBr(CO)3{(PhSCH2)2SiR1R2}] (R1, R2=Ph (4a)), (R1=vinyl, R2=Me (4b)), (R1=H, R2=Me (4c)). Due to the presence of two different substituents R1 and R2 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(CH2SPh)2Me}] (5a) and the rigid derivative [Pt(H)(PPh3)2{Si(CH2SPh)3}] (5b). The ditelluroether complexes cis-[PtCl2{(RTeCH2)2SiMe2)] (6a, R=Ph), (6b, R=n-Bu) are obtained by treatment of [PtCl2(PhCN)2] with (PhTeCH2)2SiMe2 (2a) and (n-BuTeCH2)2SiMe2 (2b), respectively. The complex fac-[ReBr(CO)3{(n-BuTeCH2)2SiMe2}] (7) results from the reaction of [Re(μ-Br)(CO)3THF]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.