Synthesis and spectroscopic characterization of cobalt(II),nickel(II)and copper(II)complexes with 5-methyl-1-(2'-pyridyl)pyrazole-3-carboxylic acid and 5-methyl-1-(4',6'-dimethyl-2'-pyrimidyl)pyrazole-3-carboxylic acid

摘要

Synthesis and characterization of cobalt(II),nickel(II)and coper(II)complexes with title ligands,1 and 2(abbreviated as PyPzCH and PymPzCH respectively)were carried out by elemental analyses,mass,IR and PMR spectral studies.Magnetic and electronic spectral features classify the reported bis-chelates as six coordinated distorted octahedral ones.A comparative study of IR spectra between the ligands and the complexes indicate different denticity of the ligands.The neutral bidentate ligand 1 functions through pyrazolyl 2_N and pyridyl 1'_N(tertiary N atoms)and the ligand 2,in its zwitter ion form(achieved during complexation)exercises tridentate behaviour through pyrazolyl 2_N,pyrimidyl 1'_N(tertiary N atoms)and carboxylic acid oxygen.Hence,the different coordination environments viz.MN_4X_2(M = Ni~(II)/Cu~(II))for ligand 1 and MN_4O_2(M = Co~(II)/Ni~(II)/Cu~(II))for ligand 2 are indicated.Electrochemical studies of some of the Cu~(II)species demonstrate easy oxidative nature of Cu~(II).