A STUDY ON THE REACTIVITY OF COBALT, COPPER AND ZINC-COMPLEXES OF 2-METHYLPYRIDINE-N-OXIDE TOWARDS SULFUR-DIOXIDE

A series of complexes of general formula M(2-PyCO)(n)X-2(H2O)(m) (M = Co, Cu, Zn; 2-PyCO = 2-methylpyridine-N-oxide, n = 1-2, X = Cl, Br, I and NO3 and m = 0-1) has been prepared and characterised. The reactivi ty of these complexes with sulfur dioxide has been investigated in the solid state and in toluene slurries at room temperature. The effect o f temperature on the ability of these-complexes to hx SO2 has been stu died by thermogravimetrical analysis (TGA); the temperature range of s tudy depending critically on the melting point of the initial precurso rs. The same technique has been used to study the reversibility of the reaction with sulfur dioxide. The amount of sulfur dioxide fixed is d ependent on the metal, the anion, the medium of the reaction and the t emperature. In general, an increase in temperature results in a decrea se in the reactivity of the metal precursors with SO2 but the complexe s of copper halides show that an increase in temperature favours the r eaction. This is quite interesting behaviour not previously reported. (C) 1998 Elsevier Science Ltd. All rights reserved.