The fragmentation patterns of nickel, palladium, and platinum dimethylglyoximes by electron and chemical ionization mass spectrometry

Abstract

Studies are reported in this thesis which include the preparation of the nickel(II), palladium(II), and platinum(II) dimethylglyoxime complexes and their mass spectra via electron ionization and chemical ionization. The method used for both modes of ionization is direct probe employing the introduction of a solid sample directly into the ion source where it is vaporized. The compositions of these compounds have been verified by decomposition points and ultraviolet and infrared spectra which are compared with values cited in the literature. Previous investigations via electron ionization for nickel dimethylglyoxime are by Jenkins and Majer and by Westmore and Fung. These two investigations, however, are not in agreement with each other regarding observations of mass peaks in the mass spectrum. This study's mass spectrum for nickel dimethylglyoxime agrees only with Westmore and Fung. The disagreement with Jenkins and Majer may be due to their miscounting of masses. For palladium and platinum dimethylglyoximes, the only recorded investigation is by Westmore and Fung. This study agrees with their findings. There are no earlier investigations by chemical ionization reported for nickel, palladium, or platinum dimethylglyloximes. This study, therefore, provides the first significant information on fragmentation patterns of the metal chelates with methane gas as the reagent. Since this is a "soft" ionization technique, fragmentation is greatly reduced in comparison to the molecular ions of electron ionization spectra. Positive-ion and negative-ion formation can occur under chemical ionization via a wide variety of ionization reactions. Only positive-ion formation by protonation, charge exchange, and adduct formation are observe in this study. The isotopic ions are observed in rations agreeing with those cited in literature for the metals. This work verifies Westmore and Fung's investigations for nickel, palladium, and platinum dimthylglyoximes. It confirms the possible miscalculations by Jenkins and Majer. This study also goes beyond earlier investigations with significant chemical ionization spectra.