Complexes of esters of pyridine carboxylic acids. Part I. Complexes with Ni(II) and Co(II) thiocyanates

Abstract

The syntheses of Nickel(II) and Cobalt(II) thio-cyanate complexes of type ML_n(NCS)₂ where M=Co or Ni and n=2 for L=methyl picolinate (MP), ethyl picolinate (EP), isopropyl picolinate (IP) and n=4 for L=ethyl nicotinate (EN) and ethyl isonicotinate (EIN), are described. The complexes have been characterised by elemental analyses, molar conductance, magnetic susceptibility, thermogravimetric, electronic and infrared spectral data. The complexes are non-electrolytes in nitrobenzene and have high spin distorted octahedral structure with N-bonded thiocyanate groups in trans-position. MP, EP and IP act as bidentate ligands coordinating through pyridine ring nitrogen and carbonyl oxygen while EN and EIN act as unidentate ligands and coordinate through ring nitrogen only. The values of splitting energy (10 Dq), Racah parameter (B) and nephelauxetic ratio (β) have been evaluated for the nickel complexes.