New Group 9 metal complexes containing N,P-chelate ligand system.: Synthesis, characterization and application to catalytic hydrogenation

New N,P-chelating o-carboranylaminophosphine ligand CabN,P2 [CabN,P=o-C2B10H10(CH2NMe2)(PPh2)-N,P] was prepared from o-carboranylamine LiCabN [CabN=o-C2B10H10(CH2NMe2)-N] and chlorodiphenylphosphine. Consequently, the reaction of [M(cod)(solv)2]+BF4− (M=Rh, Ir; cod=cycloocta-1,5-diene) with 2 was investigated. The resulting rhodium and iridium metal complexes [(CabN,P)M(cod)]+BF4−3 (M=Rh 3a, Ir 3b) were characterized by NMR spectroscopy and elemental analysis. In addition, an X-ray structure analysis was performed on complex 3a, where the potential N,P-chelate ligand 2 was found to coordinate in a bidentate mode. The subsequent reaction of 3 with PPh3 and CO resulted in the dissociation of the N,P-chelate ligand 2 to yield the penta-coordinate metal complexes [(PPh3)2M(CO)3]+BF4−4 (M=Rh 4a, Ir 4b). The structure of 4a was determined by X-ray diffraction analysis, exhibiting a trigonal bipyramidal configuration with the triphenylphosphine ligands occupying axial positions. The activities of complex 3 as a catalyst precursor during the hydrogenation of cyclohexene were tested and produced the cyclohexane with 100% conversion in the case of 3a.