Donor-atom effects in the mass spectra of complexes of dipivaloylmethane and its monothio and dithio analogues

The progressive replacement by sulphur in the isostructural planar nickel compounds bis(2,2,6,6- tetramethylheptane-3,5-dionato)nickel(11) (1), bis(2,2,6,6-tetramethyl-5-thioxoheptan-3-onato)nickel(11) (2) and bis(2,2,6,6-tetramethylheptane-3,5-dithionato)nickel(11) (3) causes a change in their positive electron impact mass spectra from one dominated by metal-containing fragment ions (1) to one But 1 dominated by oxidized ligands (3). Comparisons are also made with the spectra of tris(monothio-dipivaloylmethanato)cobalt(111) and bis(1,l,1-trifluoro-4-thioxopentan-2-onato)nickel (11). Mass spectral peaks corresponding to mixed ligand species were observed when mixtures of (1) and (2) were vaporized in the mass spectrometer.