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Abstract
New bi- and trihomonuclear Mn(II), Co(II), Ni(II), and Zn(II) complexes with sulfa-guanidine Schiff bases have been synthesized for potential chemotherapeutic use. The complexes are characterized using elemental and thermal (TGA) analyses, mass spectra (MS), molar conductance, IR, 1H-NMR, UV-Vis, and electron spin resonance (ESR) spectra as well as magnetic moment measurements. The low molar conductance values denote non-electrolytes. The thermal behavior of these chelates shows that the hydrated complexes lose water of hydration in the first step followed by loss of coordinated water followed immediately by decomposition of the anions and ligands in subsequent steps. IR and 1H-NMR data reveal that ligands are coordinated to the metal ions by two or three bidentate centers via the enol form of the carbonyl C=O group, enolic sulfonamide S(O)OH, and the nitrogen of azomethine. The UV-Vis and ESR spectra as well as magnetic moment data reveal that formation of octahedral [Mn2L1(AcO)2(H2O)6] (1), [Co2(L1)2(H2O)8] (2), [Ni2L1(AcO)2(H2O)6] (3), [Mn3L2(AcO)3(H2O)9] (5), [Co3L2(AcO)3(H2O)9] · 4H2O (6), [Ni3L2(AcO)3(H2O)9] · 7H2O (7), [Mn3L3(AcO)3(H2O)6] (9), [Co2(HL3)2(H2O)8] · 4H2O (10), [Ni3L3(AcO)3(H2O)9] (11), [Mn3L4(AcO)3(H2O)9] · H2O (13), [Co2(HL4)2(H2O)8] · 5H2O (14), and [Ni3L4(AcO)3(H2O)9] (15) while [Zn2L1(AcO)2(H2O)2] (4), [Zn3L2(AcO)3(H2O)3] · 2H2O (8), [Zn3L3(AcO)3(H2O)3] · 3H2O (12), and [Zn3L4(AcO)3(H2O)3] · 2H2O (16) are tetrahedral. The electron spray ionization (ESI) MS of the complexes showed isotope ion peaks of [M]+ and fragments supporting the formulation.