Structural motifs and biological studies of new antimony(iii) iodide complexes with thiones

Abstract

Eight new antimony(III) iodide complexes of the heterocyclic thioamides, 2-mercapto-1-methylimidazole (MMI), 2-mercaptobenzlmidazole (MBZIM), 5-ethoxy-2-mercaptobenzimldazole (EtMBZIM), 2-mercaptothiazolidine (MTZD), 3-methyl-2-mercaptobenzothiazole (NMeMBZT), 2-mercapto-3,4,5,6- tetrahydropyrlmidine (tHPMT), 2-mercaptopyrldlne (PYT), and 2-mercaptopyrimldlne (PMT) of formulas {[Sbl3(MMl)2] -MeOH} (1), [Sbl 3(MBZIM)2] (2), {[Sbl2(μ2-I) (EtMBZIM)2]2-H2O} (3), [Sbl3(MTZD)] (4), [(NMeMBZT)Sbl2(μ2-I)2(μ2- S-NMeMBZT)Sbl2 (NMeMBZT)] (5), {[Sbl3OHPMT) 3]-MeOH} (6), [Sbl3(PYT)] (7) and [Sbl3(PMT) 2] (8), have been synthesized and characterized by elemental analysis, FT-IR spectroscopy, FT-Raman spectroscopy and TG-DTA analysis. The crystal structures of 3,4,5,6, and 7 were also determined by X-ray diffraction. The complexes show interesting structural motifs. Complex 6 is a monomer, with octahedral (Oh) geometry around the metal ion formed by three sulfur and three iodide atoms. Complexes 3 and 5 are dimers, with a square pyramidal (SP) geometry in each monomeric unit, while complexes 4 and 7 are polymers with pseudotrlgonal bipyramidal (ψ-TBP). Two or three sulfur atoms from thioamide ligands and three iodide atoms are bound to Sb atoms forming building blocks for the dimers and polymers. Strong intramolecular interactions between μ2-I and/or μ2-S and Sb atoms stabilize both structures. In dimer complex 5, two terminal iodide and one terminal sulfur atom are bonded to the Sb ion, while two μ2-I and one μ2-S bridging atoms bridge the metal Ions forming ψ-Oh geometry. Computational studies using multivariant linear regression (MLR) and artificial neural networks (ANN) and considering biological results (50% inhibitory concentration, IC50) as dependent variables derived a theoretical equation for IC50 values of the complexes studied. The calculated IC50 values are compared satisfactorily with the experimental inhibitory activity of the complexes measured. Complexes 3 - 7 were used to study their influence upon the catalytic peroxidation of linoleic acid by the enzyme Lipoxygenase (LOX). Compounds 1 - 8 were also tested for In vitro cytotoxicity, and they showed mostly a moderate cytostatic activity against a variety of tumor cell lines but comparable with those found for the antimony(III) chloride and bromide complexes, reported earlier [Ozturk et al. Inorg. Chem. 2007, 46, 2861-2866

Ozturk et al. Inorg. Chem. 2009, 48, 2233-2245]. © 2009 American Chemical Society.