Ligand degradation and phosphorus scavenging in the reaction between 1,2-bis(diphenylphosphino)benzene (dppbz) and Ru 6(μ 6-C)(CO) 17: Synthesis and X-ray structure of the edge-bridged square-pyramidal cluster HRu 6(μ 5-C)(μ 3-P)(CO) 14(dppbz)

Abstract

Thermolysis or Me 3NO activation of the hexaruthenium cluster Ru 6(μ 6-C)(CO) 17 in the presence of the diphosphine ligand 1,2-bis(diphenylphosphino)benzene (dppbz) does not furnish the expected dppbz-substituted cluster Ru 6(μ 6-C)(CO) 15(dppbz) but rather HRu 6(μ 5-C)(μ 3-P)(CO) 14(dppbz), whose edge-bridged square-pyramidal structure has been established by X-ray crystallography. Accompanying the opening of the original closo Ru 6 polyhedron is the dephosphination of a second dppbz ligand through three rapid P–C bond cleavages, leading to the capture of the phosphorus atom as a face-capping phosphido ligand. This unprecedented reactivity between Ru 6(μ 6-C)(CO) 17 and the dppbz ligand is discussed relative to other diphosphine ligands.