Heterometallic cyanide-bridged complexes containing RhIRuIIRhI triad: NMR data on exchange reactions and ligand effect transmission

Trans-[RuPy4(CN)2 cleaves chloro-rhodium bridges in rhodium(I) binuclear complexes, [Rh(CO)2Cl]2, [Rh(Cod)Cl]2, and [(Cod)RhCl2Rh(CO)2] yielding heterometallic triad complexes, [(CO)2ClRh(NC)RuPy4(CN)RhCl(CO)2] (I), [(Cod)ClRh(NC)RuPy4(CN)RhCl(Cod)] (II), and [(Cod)ClRh(NC)RuPy4(CN)RhCl(CO)2] (III), respectively. In solutions, III coexists with equilibrium amounts of I and II in the near-binomial proportions. Under action of [Rh(CO)2Cl]2, II transforms into I with parallel formation of [Rh(Cod)Cl]2. Ligand effect transmission along the L-Rh-NC-Ru-CN-Rh-L′ chain is studied by 1H and 13C NMR. Chemical shifts δ1H and δ13C of Ru-bound Py ligands are sensitive to the nature of Rh-bound ligands. Values of δ1H and δ13C of Cod and 13C of CO ligands are sensitive to the ligands at the remote end of the L-Rh-NC-Ru-CN-Rh-L′ chain. Reaction of trans-[RuPy4(CN)2] with Rh2(OAc)4 yields an apparently linear polymer [-Rh(OAc)4Rh-NCRuPy4CN-]. Upon action of [Rh(CO)2Cl]2, the polymer decomposes yielding I and Rh2(OAc)4. X-ray structure data for I are given.