Water-soluble polymeric complexes of cobalt(II) and nickel(II) with azolate anions

N-Unsubstituted azoles (1,2,4-triazole, 3-amino-1,2,4-triazole) and 5-R-tetrazoles (R = H, CH3, C2H5, C4H9, CH=CH2, C6H5, p-CH3C6H4, NH2) form water-soluble polymeric complexes in systems containing certain transition metal salts. The data obtained and the results of MP2/6-31G** calculations of the electronic structures of 5-R-tetrazolate anions show that the ability of azoles for formation of polymeric complexes with transition metal ions is mostly determined by the acid-base properties of azoles. The geometric structure of a polymeric chain with the Co2+ ion having the coordination number 6 and the 5-methyltetrazolate anion being a bridging ligand was examined at the STO-3G level. It was shown that the coordination by the 2- and 3-nitrogen atoms of the tetrazole ring is most favored by energy.