Azidoacetone as a complexing agent of transition metals Ni 2+/Co2+ promoted dissociation of the C-C bond in azidoacetone

Ana C. Assis, Narciso Couto, M. Filomena Duarte, Paula Rodrigues, M. Teresa Barros, M. Lourdes Costa, Benedito J. C. Cabrald, M. Tereza Fernandez

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3 Citations (Scopus)

Abstract

The relevance of metal interactions with azides has led us to the study of the complexation of some transition metals, nickel and cobalt, by azidoacetone by means of electrospray ionization mass spectrometry (ESI-MS). Complexes were obtained from solutions of NiCl2 and CoCl2, in methanol/water. Nickel was electrosprayed with other counter ion, bromide (Br), as well as other solvent (ethanol/water). For nickel and cobalt, the complexes detected were single positively charged, with various stoichiometries, some resulted from the fragmentation of the ligand, the loss of N2 being quite common. The most abundant species were [Ni(II)Az2X]+ where X = Cl, Br and Az = azidoacetone. Some of the complexes showed solvation with the solvent components. Metal reduction was observed in complexes where a radical was lost, resulting from the homolytic cleavage of a metal coordination bond. Collision-induced dissociation (CID) experiments followed by tandem mass spectrometry (MS-MS) analysis were not absolutely conclusive about the coordination site. However, terminal ions of the fragmentation routes were explained by a gas-phasemechanism proposed where a C-C bond was activated and themetal inserted subsequently. Density functional theory calculations provided structures for some complexes. In [Ni(II)Az2X]+ species, one azidoacetone ligand is monodentate and the dominant binding location is the alkylated nitrogen and not the carbonyl group. The other azidoacetone ligand is bidentate showing coordination through alkylated nitrogen and the carbonyl group. These are also the preferential binding sites for themost stable isomer of [Ni(II)AzX]+ species.

Original languageEnglish
Pages (from-to)696-704
Number of pages9
JournalJournal Of Mass Spectrometry
Volume46
Issue number7
DOIs
Publication statusPublished - 1 Jul 2011

Keywords

  • Azidoacetone complexes
  • C-C metal insertion
  • DFT calculations
  • Electrospray ionization
  • Tandem mass spectrometry

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