Chemical and electrochemical oxidation of [Rh(-diketonato)(CO)(P(OCH2)3CCH3)]: an experimental and DFT study

An experimental and computational chemistry study of the reactivity of [Rh(-diketonato)(CO)(P(OCH 2 ) 3 CCH 3 )] complexes towards chemical and electrochemical oxidation shows that more electron withdrawing groups on the -diketonato ligand reduce electron density on the rhodium atom to a larger extent than electron donating groups. This leads to a slower second-order oxidative addition rate, k 1 , and a higher electrochemical oxidation potential, E pa (Rh), linearly related by ln k 1 = 11(1) E pa (Rh) 2.3(5). The reactivity of these complexes can be predicted by their DFT calculated HOMO energies: E HOMO = 0.34(8) E pa (Rh) 5.04(4) = 0.032(5) ln k 1 4.96(4). k 1 of [Rh(-diketonato)(CO)(P(OCH 2 ) 3 CCH 3 )] complexes is slower than that of related [Rh(-diketonato)(CO)(PPh 3 )] and [Rh(-diketonato)(P(OPh) 3 ) 2 ] complexes due to the better -acceptor ability of the COphosphiterhodium combination than that of COPPh 3 rhodium or di-phosphiterhodium. Chemical and electrochemical oxidation of [Rh(-diketonato)(CO)(P(OCH 2 ) 3 CCH 3 )].