First spectroscopical evidence of a dioxomethylene intermediate in the reaction of CO2 with Cp2Zr(H)Cl:: A 13C NMR study

An in situ variable-temperature C-13 NMR study on the mechanism of the reaction of Schwartz's reagent, Cp2Zr(H)Cl, with labeled (CO2)-C-13 was performed. In the course of the investigations, for the first time the long postulated mu-eta (1)-O,O ' gem-diolate species Cp2Zr(Cl)OCH2OZr(Cl)Cp-2 was observed.