THE REACTIVITY OF SULFUR-DIOXIDE WITH TRANSITION-METAL COMPLEXES CONTAINING 4-CYANOPYRIDINE-N-OXIDE AND 3-PYRIDYLCARBINOL-N-OXIDE - THE HIGH-TEMPERATURE ISOLATION OF A MANGANESE(II) IODIDE SO2-ADDUCT

The reactivity of metal complexes M(RPyO)(n)X-2(H2O)(m) (RPyO = 4-cyan opyridine-N-oxide or 3-pyridylcarbinol-N-oxide;M = Mn, Co, Cu; X = CI, Br, I, NO3; n = 2-4 and m = 0-3) with SO2 has been studied in toluene slurries and in the solid state at room temperature and in the solid state at high temperature. Only the metal iodide precursors containing 4-CNPyO reacted with SO2 in the solid state or in a toluene slurry bu t never above room temperature. Among the precursors containing 3-HOH2 CPyO, only the copper metal complexes interact with SO2 at room temper ature in toluene slurries. Surprisingly, Mn(3-HOH2CPyO)(2)I-2(H2O) rea cted with SO2 at 210 degrees C, whereas the metal complex was unreacti ve at room temperature. Likewise, Cu(3-HOH2CPyO)(2)(NO3)(2) reacted at 100 degrees C, the SO2 being oxidised to sulfate, displacing the nitr ate group, but not at room temperature.