Thermochemistry of thiourea complexes of the type [MII(tu)4Cl2](MII= manganese, iron, cobalt, nickel, zinc, cadmium, and mercury)

Abstract

The enthalpies of formation of crystalline and gaseous, sulphur-bonded, thiourea complexes of the type [M^II(tu)₄Cl₂], (M^II= Mn, Fe, Co, Ni, Zn, Cd, and Hg) have been measured by reaction calorimetry. Co-ordinate bond dissociation energies. (M–S), indicate that the M-S bonds in these complexes are weaker than M–O and M–N bonds in other octahedral complexes. The total metal–ligand bond energies show the effect of ligand field stabilisation which, for Fe and Ni complexes, is in accord with the spectroscopically determined values of Δ. The Co complex is less stable than expected.