Catalytic hydrogenation of carbon dioxide with the cationic bis(chelate)rhodium complex [Rh(P⌢O) 2][BPh 4

Abstract

In contrast to the mono(chelate)rhodium complex CIRh(P∼O)(P⌢O) ( 1) ( P⌢ O = η 2(O,P)- chelated Cy 2PCH 2 CH 2OCH 3 ligand; P∼O = η 1( P)-coordinated) the corresponding cationic bis(chelate) complex [Rh(P⌢O) 2] + (anion: BPh 4 −) ( 4) acts as an efficient catalyst for the hydrogenation of carbon dioxide to produce formic acid. Turnover numbers up to 1000 within 7 h are achieved in methanol solution at 55°C. Stoichiometric reactions related to the characterization of possible reactive intermediates are also presented.