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Electrospray ionization studies of transition‐metal complexes of 2‐acetylbenzimidazolethiosemicarbazone using collision‐induced dissociation and ion‐molecule reactions
Author(s) -
Bhaskar G.,
Chary M. Adharvana,
Kumar M. Kiran,
Syamasundar K.,
Vairamani M.,
Prabhakar S.
Publication year - 2005
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.1954
Subject(s) - chemistry , dissociation (chemistry) , electrospray ionization , molecule , metal ions in aqueous solution , ion , metal , transition metal , inorganic chemistry , collision induced dissociation , crystallography , deprotonation , mass spectrum , qualitative inorganic analysis , enol , mass spectrometry , tandem mass spectrometry , catalysis , organic chemistry , chromatography
Abstract The complexes of transition‐metal ions (M 2+ , where M = Fe, Co, Ni, Cu, Zn, Cd, and Hg) with 2‐acetylbenzimidazolethiosemicarbazone (L) are studied under electrospray ionization (ESI) conditions. The ESI mass spectra of Fe and Co complexes showed the complex ions corresponding to [M+2L–2H] + , and those of Ni and Zn complexes showed [M+2L–H] + ions, wherein the metal/ligand ratio is 1:2 and the oxidation state of the central metal ion is +3 in the case of Fe and Co and +2 in the case of Ni and Zn. The Cd and Cu complexes showed preferentially 1:1 complex ions, i.e., [M+L–H] + or [M+L+Cl] + , whereas Hg formed both 1:1 and 1:2 complex ions. During formation of the above complex ions one or two ligands are deprotonated after keto‐enol tautomerism, depending on the nature and oxidation state of central metal ion. The structures and coordination numbers of the metal ions in the complex ions were studied by their collision‐induced dissociation spectra and ion‐molecule reactions with acetonitrile or propylamine in the collision cell. Based on these results it is concluded that Fe, Co, Ni and Zn form stable octahedral complexes, whereas tetrahedral or square planar complexes are formed preferentially for other metals. In addition, the Cu complex showed a [2L+2Cu–3H] + ion with a CuCu bond. Copyright © 2005 John Wiley & Sons, Ltd.