Synthesis and Electrochemistry of Heterobimetallic Ruthenium/Platinum and Molybdenum/Platinum Complexes

As starting materials for heterobimetallic complexes, [RuCp(PPh3)CO(PPh2H)]PF6 and [RuCp(PPh3)CO(η1-dppm)]PF6 were prepared from RuCp(PPh3)(CO)Cl. In the course of preparing [RuCp(η2-dppm)(η1-dppm)]Cl from RuCp(Ph3P)(η1-dppm)Cl, the new monomer RuCpCl(η1-dppm)2 was isolated. The uncommon coordination mode of the two monodentate bis(phosphines) was confirmed by X-ray crystallography [a = 11.490(1) Å, b = 14.869(2) Å, c = 15.447(2) Å, α = 84.63(1)°, β = 70.55(1)°, γ = 72.92(1)°, V = 2378.7(5) Å3, dcalc = 1.355 g cm-3 (298 K), triclinic, P1̄, Z = 2]. The dppm-bridged bimetallic complexes RuCp(PPh3)Cl(μ-dppm)PtCl2, RuCpCl(μ-dppm)2PtCl2, and [RuCp(PPh3)CO(μ-dppm)PtCl2]PF6 each exhibit electrochemistry consistent with varying degrees of metal−metal interaction. The cationic heterobimetallic complexes [Mo(CO)3(μ-dppm)2Pt(H)]PF6 and [MoCp(CO)2(μ-PPh2)(μ-H)Pt(PPh3)(MeCN)]PF6 were prepared by chloride abstraction from the corresponding neutral bimetallic species and show electrochemical behavior similar to the analogous Ru/Pt complexes.