Synthesis and Reactivity of Iridium and Rhodium Silyl Complexes Supported by a Bipyridine Ligand

The rhodium and iridium complexes [((t)Bu(2)bPY)(2)M(mu-Cl)](2)(M = Rh(1), Ir(2)) containing the bidentate (t)Bubpy(4,4'-di-tert-butyl-2,2'-bipyridyl) ligand were prepared. Dimeric complexes 1 and 2 react with HSiPh3 to give [((t)Bu(2)bpy)MH(SiPh3)(mu-Cl)](2) in good yields(M = Rh(3) 92%, Ir(4) 90%). Addition of (PPr3)-Pr-i to 3 or 4 gave monomeric crystalline complexes of the type((t)Bu(2)bpy)MH(SiPh3)Cl((PPr3)-Pr-i) (M = Rh(7) and Ir(8)), which adopt a slightly distorted octahedral coordination geometry with the (t)Bu(2)bpy ligand occupying sites trans to the hydride and chloride ligands, as determined by X-ray crystallography. Salt metathesis reactions of 7 and 8 produced((t)Bu(2)bpy)MH(SiPh3)(R)P(i)Pr3 as monomeric octahedral complexes with the (t)Bu(2)bpy ligand occupying sites trans to the hydride and R substituents(M = Rh, R = H(11) and M = Ir, R = H(12), Me(14), and Ph(15)). Salt metathesis reactions with 3 and 4 also generated the dimeric, dicationic complexes [((t)Bu(2)bpy)M(SiPh3)(mu-H)](2)-[B(C6F5)(4)](2), where M = Rh(116) or Ir(17). Thermolysis of 15 at 100 degrees C in C6H6 for I day produced 12 and Ph4Si in 47% yield, and heating 15 in the presence of 1 equiv of HSiR3(R = Ph, Et) also gave 12, as well as the Si-C coupled product PhSiR3 in > 95% yield.