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 13 C NMR study on the mechanism of the reaction of Schwartz's reagent, Cp 2 Zr(H)Cl, with labeled 13 CO 2 was performed. In the course of the investigations, for the first time the long postulated μ-η 1 -O,O‘ gem -diolate species Cp 2 Zr(Cl)OCH 2 OZr(Cl)Cp 2 was observed.