| Abstract: | The mass spectra of a number of cis-disubstituted derivatives of the Group VI-B metal carbonyls (M = Cr, Mo, W), in which the substituents are bidentate ligands bonding to the metal through As, S or N donor atoms, have been obtained. The spectra for derivatives of o-phenylenebis-(dimethylarsine) (diars) have been examined in greatest detail. For these latter complexes, competitive loss of carbonyls and diars methyl groups was observed. The proposed use of such competition in the evaluation of metal-carbonyl bond strengths is examined. For complexes containing ethylene-bridged bidentate ligands, ions indicative of the loss of five fragments of 28 mass units from the parent ion, corresponding to loss of four carbonyls and the ethylene bridge, are observed. The question of whether ethylene loss occurs prior to, competitively with or after carbonyl loss is considered. |
