The stability of solid complexes can usually by characterized by the heat of formation of complexes from salts MXn and the ligand R in gaseous state. In order to evaluate the stability of a series of complexes Py2MCl2 (M=Cu, Ni, Co, Mn, Hg, Zn, Fe and Cd), the heats of formation of these complexes were measured by quantitative DTA experimentally and compared with that calculated by Yang Pin's method. Both results agree well. On the basis of these results stabilities of complexes Py2MCl2 were estimated.

Key words: STABILITY, PYRIDINE P, METAL COMPLEX, FORMATION HEAT