SIGMA-METATHESIS AS A CRITICAL STEP FOR THE TRANSITION-METAL-CATALYZED FORMATION OF FORMIC-ACID FROM CO2 AND H-2 - AN AB-INITIO INVESTIGATION

The hydrogenation of CO2 to formic acid catalyzed by three‐coordinate d8 hydridorhodium complexes has been studied by ab initio calculations on [HRh(PH3)2] as the model catalyst. A catalytic cycle involving a 2σ + 2σ metathesis reaction between H2 and [Rh(PH3)2(O2CH)], in which rhodium remains in the oxidation state I, is proposed as an alternative to the traditional pathway involving RhI/RhIII oxidation/reduction sequences. Copyright © 1995 by VCH Verlagsgesellschaft mbH, Germany