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

Abstract

New N,P-chelating o-carboranylaminophosphine ligand Cab(N,P) 2 [Cab(N,P) = o-C2B10H10(CH2NMe2)(PPh2)-N,P] was prepared from o-carboranylamine LiCab(N) [Cab(N) = 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 [(Cab(N,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)(2)M(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. (C) 2000 Elsevier Science B.V. All rights reserved.