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(μ-H)(μ-η2-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 σ-bond and a RhHSi three-centers two-electrons bond (3c-2e bond). The 1H and 31P{1H} 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)2Pt(μ-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(μ-Si(C6H4F-4)2)(dmpe)]2 (4b) as an isolated product. The complex has a symmetrical structure with two bridging diarylsilylene ligands.