Thermochemical consequences of π delocalization in metal-biguanide complexes

The thermodn. function ΔH° and ΔS° for the reaction of biguanide with Ni(II) and Cu(II) ions in 0.1 M KCl were detd. at 25°. The reaction is strongly exothermic with the formation of 1:2 metal-ligand complexes. The ligand stabilization due to π-delocalization and formation of metal-N bonds are both responsible for the high exothermic effect of the complex formation.