Issue 17, 2014

Reactivity of the drug methimazole and its iodine adduct with elemental zinc

Abstract

The reactivity of zinc complexes with N,S-donor molecules may be of relevance to the study of Zn-metalloproteins and -metalloenzymes. In this context, the zinc complex [Zn(MeImSH)2I2] was synthesised by the reaction of zinc powder with the 1 : 1 iodine adduct of the drug methimazole [(MeImSH)·I2]. The molecular structure of the complex, elucidated by X-ray diffraction analysis, showed a tetrahedral zinc(II) centre coordinated by two neutral methimazole units (through the sulfur atoms) and two iodides. From the reaction of MeImSH and Zn powder, the complex [Zn(MeImSH)(MeImS)2] (MeImS = deprotonated form of methimazole) was separated and characterised. An analysis of the crystal packing of the neutral complexes [Zn(MeImSH)2X2] (X = I, Br and Cl) and the ionic complex [Zn(MeImSH)3I]I showed that in all of the complexes the sulfur atom, in addition to binding to the metal centre, contributes to the formation of 1-D chains built via C(4)–H⋯S and N–H⋯X interactions in the neutral complexes, and via C(4)–H⋯S and N–CH3⋯S interactions in the ionic complex [Zn(MeImSH)3I]I. The deprotonation/protonation of the coordinated methimazole units can modulate the coordination environment at the Zn core. From the reaction of complex [Zn(MeImSH)3I]I with a strong non-coordinating organic base, we have shown that, as a consequence of the NH deprotonation of methimazole S-coordinated to zinc(II), the ligand coordination mode changes from S-monodentate to N,S-bridging. Correspondingly, in the complex [Zn(MeImSH)(MeImS)2], the MeImS that displays the N,S-bridging mode at zinc can be N-protonated and thereby changes to the S-monodentate coordination.

Graphical abstract: Reactivity of the drug methimazole and its iodine adduct with elemental zinc

Supplementary files

Article information

Article type
Paper
Submitted
21 Dec 2013
Accepted
17 Feb 2014
First published
17 Feb 2014
This article is Open Access
Creative Commons BY license

CrystEngComm, 2014,16, 3613-3623

Reactivity of the drug methimazole and its iodine adduct with elemental zinc

F. Isaia, M. C. Aragoni, M. Arca, C. Caltagirone, A. Garau, P. G. Jones, V. Lippolis and R. Montis, CrystEngComm, 2014, 16, 3613 DOI: 10.1039/C3CE42601G

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