Ab initio study of stable bis(carbon dioxide)molybdenum complexes

Ab initio valence calculations of double-ζ quality using atomic pseudo-potentials have been carried out for the bis(carbon dioxide) complexes, trans-[Mo(CO2)2(PH3)4] and trans,mer-[Mo(CO2)2(CNH)(PH3)3]. The conformational preferences of the CO2 ligands for the former complex have been investigated. The most stable conformation has the two carbon dioxide ligands mutually perpendicular and eclipsing the Mo–P bonds. The main carbon dioxide–metal interactions, as well as the effects of the substitution of a PH3 ligand by a CNH ligand in the equatorial plane, are discussed.