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

摘要

Two cobalt(III) complexes [Co(L~1)2]ClO4 (1) [HL~1= N-ethyl-2-((5-methyl-1H-pyrazol-3-yl)methylidene)hydrazinecarbo-thioamide] and [Co(L~2)2]ClO4.CH3OH.H2O (2) [HL~2=N,N-dimethyl-2-((5-methyl-1H-pyrazol-3-yl)methylidene) hydrazine-carbofhioamide] and one nickel(II) complex [Ni(HL~3)2](ClO4)2.2H2O (3) [HL~3=(2E)-N-ethyl-2-((6-methyl-2-(methyl-sulfanyl)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 (1 and 2) and the two similar neutral pyrimidine derived ligands in the nickel(II) complex (3) are coordinated to the central metal ions in the meridional fashion. The pyrazole N and thiolato S in (1) and (2) and pyrimidine N and thione S in (3) are cis to each other while azomethine N atoms are trans coordinated.