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)3H 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)3H and HCO2H has been studied by 1H-NMR spectroscopy, which indicates that the initial interaction involves protonation of the molybdenum center to give [Cp*Mo(PMe3)3H2][HCO2]; upon heating to 80 °C, however, [Cp*Mo(PMe3)3H2][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)(η1-O2CH); the latter complex undergoes decarboxylation at 80 °C 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 H2. Although the formate complex Cp*Mo(PMe3)2(CO)(η1-O2CH) has not been isolated, the molecular structure of the acetate derivative Cp*Mo(PMe3)2(CO)(η1-O2CMe) has been determined by X-ray diffraction.