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First cobalt complexes with methyl pyruvate semi/thiosemicarbazone - synthesis, physico-chemical and structural characterization

Rodić Marko V. (University of Novi Sad, Faculty of Sciences, Novi Sad, Serbia)
Miškov-Pajić Vukoslava (University of Stuttgart, Stuttgart, Germany)
Leovac Vukadin M. (University of Novi Sad, Faculty of Sciences, Novi Sad, Serbia)
Radanović Mirjana M. (University of Novi Sad, Faculty of Sciences, Novi Sad, Serbia)
Vojinović-Ješić Ljiljana S. (University of Novi Sad, Faculty of Sciences, Novi Sad, Serbia)
Belošević Svetlana K. (Faculty of Technical Sciences, University of Priština, Kosovska Mitrovica, Serbia)
Jaćimović Željko K. (Faculty of Metallurgy and Technology, University of Montenegro, Podgorica, Montenegro)
Živković-Radovanović Vukosava (Faculty of Chemistry, University of Belgrade, Belgrade, Serbia)

In the reaction of acetone solutions of CoX2∙nH2O (X = Cl, Br) with methyl pyruvate semi/thiosemicarbazone (Hmps, Hmpt) the first Co(II) complexes with these ligands, i.e., [Co(Hmps)(H2O)X2] (X = Cl (1), Br (2)), [Co(Hmpt)2][CoCl4]∙2H2О (3) and [Co(Hmpt)2]Br2∙Me2CO (4) were obtained. Complexes 1 and 2 represent the first examples of metal complexes of Hmps. All the obtained compounds were characterized by elemental analysis, conductometry, magnetic measurements, and IR spectra, and for complexes 2–4, single crystal X-ray diffraction analysis was also performed. The effective magnetic moments were close to the upper limit (5 μB) for complexes 1 and 2, and close to the lower limit (4.4 μB) for complexes 3 and 4, and as such are characteristic for high-spin Co(II) complexes. Structural analysis showed that both ligands coordinate in a neutral form in a tridentate manner, via the ester oxygen, imine nitrogen and the oxygen atom of the ureido (Hmps), or the sulfur atom of the thioureido group (Hmpt). The central metal atoms are situated in a deformed octahedral coordination environment. Complex 2 has cis-Br configuration, while complexes 3 and 4 have mer-configuration.

Keywords: cobalt complexes, hydrazones, single crystal X-ray analysis

Projects of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172014 and Grant no. III41010