Carbonyl abstraction reactions of Cp*Mo(PMe3)3H with CO2, (CH2O)n, HCO2H, and MeOH:: the synthesis of Cp*Mo(PMe3)2(CO)H and the catalytic decarboxylation of formic acid

CP*MO(PMe3)(3)H undergoes carbonyl abstraction reactions with a variety of reagents, including CO2, (CH2O)(n), HCO2H, and MeOH to yield CP*MO(PMe3)(2)(CO)H. The reaction between CP*MO(PMe3)(3)H and HCO2H has been studied by H-1-NMR spectroscopy, which indicates that the initial interaction involves protonation of the molybdenum center to give [Cp*Mo(PMe3)(3)H-2][[HCO2]: upon heating to 80 degreesC, however, [CP*Mo(PMe3)(3)H-2][HCO2] is converted to the carbonyl complex CP*MO(PMe3)(2)(CO)H. In the presence of excess HCO2H, Cp*Mo(PMe3)(2)(CO)H reacts further to yield CP*Mo(PMe3)(2)(CO)(eta(1)- O2CH); the latter complex undergoes decarboxylation at 80 degreesC and regenerates CP*Mo(PMe3)(2)(CO)H. Thus, CP*MO(PMe3)(2)(CO)H serves as a catalyst for the decomposition of HCO2H to CO2 and H-2. Although the formate complex CP*Mo(PMe3)(2)(CO)(eta(1)-O2CH) has not been isolated, the molecular structure of the acetate derivative Cp*Mo(PMe3)(2)(CO)(eta(1)- O2CMe) has been determined by X-ray diffraction. (C) 2002 Published by Elsevier Science B.V.