- Initial investigations into the reactions of organomagnesium halide reagents with metal carbonyls indicate this reaction to be adaptable to relative rate studies of nucleophilic attack on the carbonyl carbon. New carbene type complexes as well as preliminary rate studies are presented. Force constants and integrated infrared intensities of the CO stretching vibrations in M(CO) 5 L compounds suggest the carbene ligand to be bound to the metal in a manner similar to phosphines and phosphites and significantly different from purely sigma donating amine ligands. Dipole moment derivative calculations and band shape analyses of the CO vibrations in metal carbonyl carbene complexes are described. 1971.