HETEROBIMETALLIC ALKYL POLYHYDRIDE COMPLEXES OF RHENIUM AND PLATINUM

The utilization of the rhenium heptahydride complex [ReH7(dbpe)] [dbpe = Bu(2)(t)P(CH2)(2)-PBu(2)(t)] in reactions with bis(alkene) complexes of platinum has facilitated the isolation of the heterobimetallic alkyl polyhydride complexes [Re(dbpe)H6Pt(R')(PR(3))] [R' = C2H5, PR(3) PCy(3) (Cy = cyclohexyl); R' = C7H11 (2-norbornyl), PR(3) = PPh(3), PCy(3), PBu(3)(t)], which are resistant to the reductive elimination of alkane. The crystal structure of [Re(dbpe)H6Pt-(C2H5)(PCy(3))] was elucidated by X-ray crystallography. The molecule was shown to have a short Re-Pt bond [2.643(1) Angstrom]. For the case R' = 2-norbornyl and PR(3) = PBu(3)(t), the p-elimination of norbornene is observed, resulting in the formation of the bimetallic heptahydride complex [Re(dbpe)H7Pt(PBu(3)(t))]. The complex [ReH7(dbpe)Pt(PCy(3))] may be made by the direct reaction of [Pt(cod)(2)] with [ReH7(dbpe)] and PCy(3). All of the bimetallic complexes undergo H/D exchange reactions in C6D6 at ambient temperatures, with both metal hydride and methyl protons of the dbpe ligand being active. The reaction between [ReH7(dbpe)] and [Pt(nb)(3)] (nb = norbornene) affords a species capable of polymerizing norbornene.