ELECTROSPRAY MASS-SPECTROMETRIC STUDIES OF SOME CATIONIC AND ANIONIC GROUP-6 AND GROUP-7 METAL-CARBONYL-COMPLEXES

Electrospray mass spectra derived from dichloromethane or dichloromethane/methanol solutions of cationic and anionic metal carbonyl compounds are reported for the first time. The cations investigated are the seven coordinate species [M(CO)2(P-P)2X]+ (M = Mo, W; P-P = diphosphine or similar ligand; X = F, Cl, Br, 1) and carbonyl phosphonium or arsonium cations of the types [M(CO),(eta5-P-PMe)(eta2-P-P)]+ (M = Cr, Mo, W), [M'(CO)2(eta1-P-Me)(eta2-P-P)X]+ (M'= Mn, Re). These cations were prepared by the action of Mel on M(CO)3(eta1-P-P)(eta2-P-P) and M'(CO)2(eta1-P-P)(eta2-P-P)X, respectively, each of which contains a pendant Group 15 atom. The anionic species investigated are [M(CO)5X]- and [M'(CO)4X2]-. In all cases the dominant peak in the mass spectrum corresponds to the principal ion known to be present in solution.