Rh-Pt heterobimetallic and diplatinum complexes with bridging silyl and silylene ligands

Platinum complexes Pt(SiHAr2)(2)(PMe3)(2) (Ar = C6H5, C6H4F-4) react with RhCl(PMe3)(3) to afford Rh-Pt heterobimetallic complexes with bridging diarylsilyl and hydrido ligands, (Me3P)(Ar2ClSi)Pt(mu-H(mu-eta(2) -HSiAr2)Rh(PMe3)(3) (1a: Ar C6H5, 1b: Ar = C6H4F-4). The reaction is accompanied by the formation of small amounts of fac-RhH2(SiClAr2)(PMe3)(3) (2a: Ar C6H5, 2b: Ar = C6H4F-4). X-ray crystallography of 1a shows a square-planar coordination around Pt and an octahedral coordination around Rh. The diarylsilyl ligand is bridged unsymmetrically to the two metal centers via a Si-Pt sigma-bond and a Rh-H-Si three-centers two-electrons bond (3c-2e bond). The H-1 and P-31 {H-1} NMR spectra indicate exchange, on the NMR time scale, between the hydrido and Si-H hydrogen and PMe3 ligands bonded to Rh. Crystallographic result of (Me3P)(2)Pt(mu-SiAr2)RhH2(SiClAr2)(PMe3)(2) (3b: Ar = C6H4F-4), which was obtained in a trace amount in a solution of 1b, shows bridging diarylsilylene and hydrido ligands as well as a nonbridging hydrido ligand bonded to Rh. Heating of a mixture of Pt(SiH(C6H4F-4)(2))(2)(PMe3)(2) and PdMe2(dmpe) (dmpe = 1,2-bis(dimethylphosphino)ethane) produces [Pt(mu-Si(C6H4F-4)(2))(dmpe)](2) (4b) as an isolated product. The complex has a symmetrical structure with two bridging diarylsilylene ligands. (C) 2003 Elsevier Science B.V. All rights reserved.