Studies in negative ion mass spectrometry. XIII—Electron attachment to a series of Nickel(II) β-diketonate complexes

Results of electron attachment reactions and negative ion mass spectra are presented for a group of selected nickel(II) β-diketonate complexes of formula NiR¹COCHCOR²]₂, where R¹ is a perfluoroalkyl group and R² either an alkyl or aryl group. Molecular negative ions together with ligand ions are the major contributors to the total ion currents for each compound, and the degree of fragmentation has been shown to be dependent on the substituents R¹ and R². Fragmentation schemes have been elucidated for all the major ion decomposition pathways, and all significant ions have been identified in the negative ion mass spectra of each compound. Bis(1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedionato) nickel(II), with R¹?CF₃ and R²?tert-butyl is the complex which shows considerable potential for analytical quantitation in the negative ion mode, because of the stability of its negative molecular ion, the high negative ion yield given after electron attachment, as well as the volatility of the compound.