摘要:
The monosubstituted dinuclear complex [Rh2(mu-bzta)2(CO)3(PPh3)] (3) has been isolated from the reaction of the tetracarbonyl complex [{Rh(mu-bzta)(CO)2)2] (1) with triphenylphosphine. The crystal structural analysis of 3 has confirmed this complex to be dinuclear. The two metal centres exhibit distorted square-planar coordination and are bridged by two bzta ligands in a cis,cis and head-to-tail arrangement. The added PPh3 group has been located trans to a S atom of the bridging ligand. In solution, complex 3 is in dynamic equilibrium with 1 and the disubstituted complex [{Rh(mu-bzta)(CO)(PPh3)}2] (2) as a result of a reorganization process. Scrambling experiments carried out with related 6-methylbenzothiazole-2-thiolate complexes suggest that polynuclear intermediates are responsible for the ligand-redistribution equilibrium. Addition of further triphenylphosphine to the equilibrium mixture gives 2 quantitatively. Complex 2 reacts with triphenylphosphine to give the mononuclear complex trans-[Rh(bzta)(CO)(PPh3)2] (8) in high yield, as a result of a bridge-splitting reaction.