INTERACTION OF MnLX2 COMPLEXES WITH SULFUR DIOXIDE

Complexes of stoichiometry MnLX 2 (L = tertiary phosphine, X = halogen) have been prepared as films on infrared windows. The complexes were exposed to SO 2 /evacuation cycles with their infrared spectra monitored before and after periods of exposure. For low pressure, relatively brief exposure times, a series of MnLX 2 /SO 2 adducts were obtained which were reversible in that the SO 2 could be removed upon evacuation. However, a competitive decomposition channel existed, which was accentuated by longer exposures and higher pressure, which produced irreversible complexes having stoichiometry MnLX 2 · ½SO 2 . Dioxygen was found to displace SO 2 from the reversible adducts, and SO 2 decomposed the dioxygen adducts to a mixture of the phosphine oxide complex and the irreversible SO 2 adduct. It has been postulated that SO 2 interacts with the polymeric MnLX 2 complexes through bridging coordination involving more than one of the atoms of SO 2 .