SPECTROPHOTOMETRIC DETECTION OF SULFUR DIOXIDE- SOLUTION EQUILIBRIUM WITH MANGANESE(II) PYRIDINE-N-OXIDE COMPLEXES.

Manganese(II) complexes with pyridine-N-oxide were shown to bind SO2. Complexes of the formula Mn(Pyr-N-O)nX2 (n=2,3,4 and 6; X= Cl,Br,I) were capable of binding SO2 as judged by solid uptake studies. The complexes Mn(L)3I2 and Mn(L)2Br2 (L = Pyridine-N-Oxide) exhibited reversible binding of SO2. They could bind SO2 and release it when subjected to vacuum. The sulfur dioxide binding by tetrahydrofuran solutions of Mn(L)nI2  complexes is accompanied by an intense color formation. Spectrophotometric detection of sulfur dioxide can be achieved by monitoring changes in the intensity of the spectra of THF solutions of these complexes. Solution isotherms have been constructed. From these isotherms, the solution equilibrium constants and the affinity of these complexes towards sulfur dioxide have been determined.