Electrochemical generation of hydridopentamminerhodium(III) and its reaction with molecular oxygen

Abstract

The electrochemistry of Rh(NH₃)₅OH²⁺ has been studied in a buffered ammoniacal solution. The polarographic reduction wave at the dropping mercury electrode had E_1/2⁰ equal to −1.10 V (vs. saturated calomel electrode) in a 0.10 M NH₃ – 0.10 M NH₄ClO₄ electrolyte, and gross Hg cathode electrolysis at −1.19 V produced a stable Rh(NH₃)₅H²⁺ hydride species. Both reductions were found to take place through a Rh(I) intermediate.The reaction of the Rh(NH₃)₅H²⁺ with molecular O₂ in the ammoniacal electrolyte was also studied. The product was demonstrated to be a stable Rh(NH₃)₄(OH)(O₂H)⁺ hydroperoxo species.