Chemical evidence of polynuclear intermediates in a ligand redistribution equilibrium between dinuclear rhodium complexes. X-ray structure of (bzta = benzothiazole-2-thiolate)

Article abstract of DOI:10.1016/0022-328X(93)80403-X

The monosubstituted dinuclear complex (3) has been isolated from the reaction of the tetracarbonyl complex <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 <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- (8) in high yield, as a result of a bridge-splitting reaction.