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) ų, d_calc = 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.