Study on single crystal structure of the antimony(III) bromide complex with 3-methyl-2-mercaptobenzothiazole and biological activity of some antimony(III) bromide complexes with thioamides

Abstract

Crystals of the [SbBr3(MMBZT)2] (1) complex (MMBZT = N-methyl-2-mercaptobenzothiazole) were grown from acetonitrile/methanol of the filtrate derived from the reaction between 3-methyl-2-mercaptobenzothiazole (MMBZT) in methanol, with antimony(III) bromide in acetonitrile. The crystal structure of 1 (C16H14Br3N2S4Sb) was determined by X-ray diffraction at 100(2) K, in space group P-1, with a = 10.738(2) A, b = 11.387(3) A, c = 11.439(3) A, α = 62.764°, β = 63.36(2)°, γ = 85.074(2)°, and Z = 2. The geometry around the metal center of complex 1 is square pyramidal, with two sulfur atoms from thione ligands and three bromide anions around Sb(III). Complex is monomer. The equatorial plane is formed by two sulfur and two bromide atoms in complex, in a cis-S, cis-Br arrangement. The in vitro cytotoxicity against leiomyosarcoma cells (LMS) of antimony(III) bromide complexes with thioamide ligands with formulae: [SbBr3(MMBZT)2] (1), [SbBr3(TU)2] (2), [SbBr3(MMI)2] (3), {[SbBr2(MBZIM)4]+·[Br]−·H2O} (4), {[SbBr2(μ 2-Br)(MMBZIM)2]2} (5), {[SbBr2(μ 2-Br)(EtMBZIM)2]2·MeOH} (6), {[SbBr3(μ 2-S-tHPMT)(tHPMT)] n } (7), {[SbBr2(μ 2-Br)(PYT)2) n } (8), {[SbBr2(μ 2-Br)(MTZD)2] n } (9), and {[SbBr5]2−[(PMTH2 +)2]} (10) (where TU = thiourea, MMI = methylimidazole, MBZIM = 2-mercaptobenzimidazole, MMBZIM = 2-mercapto-5-methyl-benzimidazole, EtMBZIM = 5-ethoxy-2-mercaptobenzimidazole, tHPMT = 2-mercapto-3,4,5,6-tetrahydro-pyrimidine, PYT = 2-mercaptopyridine, MTZD = 2-mercapto-thiazolidine, and PMTH = 2-mercaptopyrimidine) were evaluated. Complex 8 shows the strongest activity against LMS cells with IC50 value 1.7 ± 0.1 μΜ. The results are compared with their activity against human cervix carcinoma cell lines. Complexes 1, 6–9 were also tested for their inhibitory activity upon the catalytic peroxidation of linoleic acid to hydroperoxylinoleic acid by the enzyme lipoxygenase. Computational studies using multivariate linear regression 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 adequately with the experimental inhibitory activity of the complexes measured.