Catalytic reduction of dimethylsulfoxide by molecular hydrogen using rhodium(III) complexes

Dimethylsulfoxide is reduced by molecular hydrogen under mild conditions to dimethylsulfide and water in the presence of rhodium(III) complexes as catalysts. The kinetics of the systems using RhCl₃.3H₂O and cis-RhCl₃(Et₂S)₃ have been investigated, and a mechanism involving reduction of coordinated dimethylsulfoxide in a rhodium(III) hydride complex is postulated. The catalytic efficiency of the systems decreases slowly due to the production of inactive rhodium(I) species.