EFFECTS OF CHANGES IN THE LIGANDS ON THE SKELETON AND THE CATALYTIC ACTIVITY OF SOME NEW RHODIUM COMPLEXES WITH PYRAZOLATO MOIETIES

Whereas the reaction of [Rh(CO)2(mu-pz)]2 (where pz is either a pyrazo lato or 3,5-dimethylpyrazolato group) with 3-(diphenylphosphino)benzoi c acid and (2-formylphenyl)diphenylphosphine gives the dinuclearic com plexes [Rh(CO)(Ph2P-3-C6H4COOH)(mu-pz)]2 (1 and 2) and [Rh(CO)(Ph2P-2- C6H4CHO)(mu-PZ)]2 (5 and 6) respectively, 2-(diphenylphosphino)benzoic acid gives the mono-rhodium compounds Rh(CO)(H-pz)(Ph2P-2-C6H4COO) (3 and 4). The structures of Rh(CO)(N=CHCH=CHNH)(Ph2P-2-C6H4COO) (3) and [Rh(CO)(Ph2P-2-C6H4CHO)(mu-NCMe=CHCMe=N)]2 (6) have been determined b y X-ray diffraction analyses. Both, the monorhodium and the dirhodium. complexes catalyse the hydroformylation of acyclic and cyclic olefins at 120-degrees-C and at CO and H-2 pressures of 28 atm. At 70-90-degr ees-C the dinuclear complexes with 3-(diphenylphosphino)benzoic acid m oieties are substantially more active than the monorhodium compounds.