Mixed Ligand Complexes of Cobalt(II): Synthesis, Reactivity, Physico-Chemical and Spectroscopic Studies

Abstract

The mixed ligand complexes of Co(II) metal ions with some heterocyclic nitrogen bases along with 1-cyano-1-carboethoxyethylene-2,2-dithiolate ion (CED2−) of the compositions, Co(N-N)(CED)·2H2O [N-N = o-phen/2,2′-bipy] and Co(N-N)(CED)L2 [N-N = o-phen/2,2′-bipy, CED2– = 1-cyano-1- carboethoxyethylene-2,2-dithiolate, L = γ-picoline (γ-pic), β-picoline (β-pic), α-picoline (α-pic), pyridine (py)] were characterized and isolated by analytical data as well as physico-chemical methods for example infrared spectroscopy, electronic, magnetic susceptibility, molar conductance. The complexes are soluble in coordinating solvents like DMSO and DMF and decompose below 250 ºC. The synthesized complexes in DMF solution are non-electrolytic as shown by their molar conductance data. The calculated magnetic moments suggest that the synthesixed cobalt(II) compounds are paramagnetic and produce a low-spin environment for the Co(II) ion. Thermal studies reveal that Co(N-N) contains two coordinated water molecules (CED)·2H2O. Electronic spectra of cobalt(II) complexes with mixed ligands in DMF solution are consistent with distorted octahedral stereochemistry. The IR studies indicates that the CED2- ion exhibits bidentate chelating behaviour and that heterocyclic nitrogen donors coordinate to Co atoms (II). Reaction with heterocyclic nitrogen donors (γ-picoline, β-picoline, α-picoline, pyridine) signifying the ligand exchange reaction.