Kinetic Study of the Insertion and Deinsertion of Carbon Dioxide into fac-(CO)3(dppe)MnOR Derivatives

The insertion of carbon dioxide into the Mn−O bond of fac -(CO) 3 (dppe)MnOCH 3 ( 1 ) was observed to occur instantaneously at −78 °C by in situ infrared spectroscopy. The product of carboxylation of 1, fac -(CO) 3 (dppe)MnOC(O)OCH 3 ( 2 ), underwent decarboxylation with a first-order rate constant of 1.49 × 10 - 4 s - 1 at 23 °C. The kinetic parameters for this process were determined by trapping the intermediate produced upon CO 2 extrusion, complex 1, with COS to provide the very stable fac -(CO) 3 (dppe)MnSC(O)OCH 3 ( 3 ) derivative. The structure of 3 was determined by single-crystal X-ray diffraction analysis, establishing the presence of the Mn−S bond.