Heterobimetallic complexes with dppm-bridged Ru/Pd, Ru/Pt, Ru/Au and Ru/Cu centers

The heterobimetallic Ru/Pd, Ru/Pt, Ru/Au and Ru/Cu complexes Cp(PPh3)Ru((mu)-I)((mu)-dppm)PdCl2(4), Cp(PPh3)Ru((mu)-Cl)((mu)dppm)Pd(CH3)Cl (5), Cp(PPh3)Ru((mu)-I)((mu)-dppm)PtCl2(6), Cp(PPh3)Ru((mu)-I)((mu)-dppm)PtI2(7), Cp(PPh3)RuI((mu)-dppm)AuI (8), Cp(PPh3)RuBr((mu)-dppm)AuCl (9), Cp(PPh3)RuCl[(mu)-PPh2(CH2)4PPh2]AuCl (10), Cp(PPh3)RuCl((mu)-Ph2PNHPPh2)AuCl (11) and Cp(PPh3)Ru((mu)-I)((mu)-dppm)CuI (12) were prepared by the reactions of CpRu(PPh3)((eta)1-Ph2PQPPh2)X [Q =(CH2)n(n= 1, 4), NH; X = Cl, Br, I, Me] with Pd(COD)Cl2, Pt(COD)Cl2, Pt(COD)I2, Au(PPh3)Cl, AuI, AuCl and CuI, respectively. The structures of compounds 4, 5, 10 and 12 were determined by X-ray crystallography. Cyclic voltammetry of the halide-bridged complexes revealed shifts in the redox potentials of the metals, as compared to mononuclear model compounds. The shifts are consistent with electron donation between the metals through the halide bridge. Ru/Au complexes 8-11, which are bridged only by the bidentate phosphine, exhibited minimal electronic effects between the metal centers. This limited interaction between the metal centers in 8-11 is corroborated by UV/vis spectroscopy.