Dipalladium complexes with bridging diorganosilyl ligands. Synthesis, structure, and properties of [LPd(mu-SiH(R)Ph)](2) (R = Ph or Me; L = PMe3, PEt3 or PMePh2)

The complexes trans-PdEt2L2 (L=PMe3, PEt3 or PMePh2) reacted with equimolar or twofold molar amounts of H2SiPh2 to produce various bimetallic palladiu m(II) complexes with bridging diphenylsilyl ligands, [(Me3P)Pd(mu-SiHPh2)]( 2) 1, (Me3P)Pd(mu-SiHPh2)Pd(PMe3)(2) 2 and [LPd(mu-SiHPh2)](2) (L=PEt3 3 or PMePh2 4), in moderate to good yields. Similar reactions using H2SiMePh af forded the complexes [LPd(mu-SiHMePh)](2) (L=PMe3 5 or PEt3 6). The isolate d complexes were characterized by NMR spectroscopy and elemental analyses. Molecular structures of 3 and 5 have been determined by X-ray crystallograp hy and suggest an agostic interaction between the mu-SiHPh2 or mu-SiHMePh g roup and the Pd. The NMR study of the complexes revealed the bridging co-or dination of the silyl ligand with the Si-H-Pd three-center, two-electron bo nd in solution similar to that in the solid state. Complex 2 undergoes exch ange of the PMe3 ligands on the NMR timescale. The reactions of 2 with CO a nd HSPh afforded 1 and Pd(SPh)(2)(PMe3)(2), respectively.