Synthesis and structural studies of cobalt(III) complexes of 5-methyl- 3-formylpyrazole-N(4)-ethyl/dimethyl thiosemicarbazone and nickel(II) complex of 2-S-methyl-6-methyl-4-formylpyrimidine-N(4)-ethyl thiosemicarbazone

Abstract

Two cobalt(III) complexes [Co(L¹)₂]ClO₄ (<b style="">1</b>) [HL¹= <i>N</i>-ethyl-2-((5-methyl-1<i>H</i>-pyrazol-3-yl)methylidene)hydrazine­carbo­thioamide] and [Co(L²)₂]ClO₄.CH₃OH.H₂O (<b>2</b>) [HL²=<i>N</i>,<i>N</i>-dimethyl-2-((5-methyl-1<i>H</i>-pyrazol-3-yl)methylidene) hydra­zine­carbothioamide]and one nickel(II) complex [Ni(HL³)₂](ClO₄)₂.2H₂O (<b>3</b>) [HL³=(2<i>E</i>)-<i>N</i>-ethyl-2-((6-methyl-2-(methyl­sulfanyl)pyrimidin-4-yl)methylidene)-hydrazinecarbothioamide] have been prepared and characterized by spectro­scopic studies and X-ray diffraction measurements. Structural study reveals that the coordination environment around each metal center is distorted octahedral. The two tridentate (NNS) uninegative pyrazole derived ligands in the cobalt(III) complexes (<b style="">1</b> and <b style="">2)</b> and the two similar neutral pyrimidine derived ligands in the nickel(II) complex (<b style="">3</b>) are coordinated to the central metal ions in the meridional fashion. The pyrazole N and thiolato S in (<b style="">1)</b> and (<b style="">2)</b> and pyrimidine N and thione S in (<b style="">3</b>) are <i>cis</i> to each other while azomethine N atoms are trans coordinated.