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-mercaptobenzimidazole (MBZIM), 5-ethoxy-2-mercaptobenzimidazole (EtMBZIM), 2-mercaptothiazolidine (MTZD), 3-methyl-2-mercaptobenzothiazole (NMeMBZT), 2-mercapto-3,4,5,6-tetrahydropyrimidine (tHPMT), 2-mercaptopyridine (PYT), and 2-mercaptopyrimidine (PMT) of formulas {[SbI(3)(MMI)(2)].MeOH} (1), [SbI(3)(MBZIM)(2)] (2), {[SbI(2)(mu(2)-I)(EtMBZIM)(2)](2).H(2)O} (3), [SbI(3)(MTZD)] (4), [(NMeMBZT)SbI(2)(mu(2)-I)(2)(mu(2)-S-NMeMBZT)SbI(2) (NMeMBZT)] (5), {[SbI(3)(tHPMT)(3)].MeOH} (6), [SbI(3)(PYT)] (7), and [SbI(3)(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 pseudotrigonal bipyramidal (psi-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 mu(2)-I and/or mu(2)-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 mu(2)-I and one mu(2)-S bridging atoms bridge the metal ions forming psi-Oh geometry. Computational studies using multivariant linear regression (MLR) and artificial neural networks (ANN) and considering biological results (50% inhibitory concentration, IC(50)) as dependent variables derived a theoretical equation for IC(50) values of the complexes studied. The calculated IC(50) 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].

Synthesis and Characterization of Antimony(III) Complexes of Thioamides, and Crystal Structure of {[Sb(Imt)2Cl2]2((2‐Imt)}Cl2(Imt=Imidazolidine‐2‐thione)

“…The central six-coordinated antimony atom is adopting pseudo octahedral geometry constituted by two terminal Imt, one bridging Imt and three chlorido ligands. Such ionic species have also been observed for some other antimony complexes for example, [Sb(MBZIM) 4 Cl 2 ]Cl•(H 2 O)(CH 3 OH) 6 and [Sb(MBZI-M) 4 Br 2 ]Br•(H 2 O) (MBZIM＝benzimidazole-2-thione).…”

“…[17][18][19] Structural studies on antimony(III) complexes of thioamides have shown that antimony(III) is quite variable in the geometries of its sulfur coordination which can vary between square pyramidal, trigonal bipyramidal and octahedral. [4][5][6][7][8][20][21][22][23][24] The structures are usually distorted because the lone pair of electrons on antimony atom affects the ideal geometry as expected from Valence Shell Electron Pair Repulsion Theory. [4][5][6] These studies further demonstrate that thiones can act both as terminal or bridging ligands [4][5][6][7][8][9][21][22][23][24] leading to the formation of polymeric structures, such as [SbBr 3 (µ 2 -Diaz)(Diaz)] n (Diaz ＝ Diazinane-2-thione).…”

“…[4][5][6][7][8][20][21][22][23][24] The structures are usually distorted because the lone pair of electrons on antimony atom affects the ideal geometry as expected from Valence Shell Electron Pair Repulsion Theory. [4][5][6] These studies further demonstrate that thiones can act both as terminal or bridging ligands [4][5][6][7][8][9][21][22][23][24] leading to the formation of polymeric structures, such as [SbBr 3 (µ 2 -Diaz)(Diaz)] n (Diaz ＝ Diazinane-2-thione). 5 We have been interested in the spectral and structural chemistry of several metal ions with thiones [25][26][27][28][29][30][31][32] in order to study their binding modes and to provide useful models for metalloproteins.…”

Novel Antimony(iii) Halide Complexes With Some N-Alkyl Thioureas: Synthesis, Characterization and Study of Their Effect Upon the Catalytic Oxidation of Linoleic Acid to Hydroperoxylinoleic Acid by Lipoxygenase

“…The degree of lipoxygenase activity (A, %) in the presence of these compounds was calculated according to the process described previously [38]. inhibition with other antimony (III) compounds, they display lower lipoxygenase inhibition than the tin compounds in the literature [14,38].…”

“…melglumineantimoniate (Glucantime) and sodium stibogluconate (Pentostam)) [9]. The potential anticancer activity of antimony compounds is under consideration [9][10][11][12][13][14][15][16][17][18][19][20][21][22]. The last studies indicated that antimony(III) compounds are more active against carcinoma than lymphoma [17].…”