Reactions of SO2 with trans-Ir(CO)(Cl)(TPPTS)2 in water

Abstract

Reaction of SO2 with trans-Ir(CO)(Cl)(TPPTS)2 in water mirrors the nature of SO2 dissolved in water. At low pH (pH = 1) where SO2 exists as the hydrated species SO2·H2O, only Ir(CO)(Cl)(SO2)(TPPTS)2 forms. At higher pH (pH = 6) where HSO3– dominates, no SO2 complex is observed and a hydride, Ir(CO)(Cl)(H)(OH)(TPPTS)2, is the primary product. A mixture of SO2 and O2 does not lead to an iridium sulfate or show any evidence of the dioxygen adduct upon reaction in water with trans-Ir(CO)(Cl)(TPPTS)2, in contrast to the analogous reaction in organic solvents. In water, only the SO2 complex, Ir(CO)(Cl)(SO2)(TPPTS)2, is observed prior to decomposition. The contrasts to the PPh3 analogues in organic solvents provide further insight to water as a solvent for organometallic complexes.Key words: iridium(I), sulfur dioxide, water soluble, TPPTS.