Synthesis and Characterization of Nb(OR)4[OC(O)OR] (R = Me, Et, Allyl) and Their Reaction with the Parent Alcohol To Afford Organic Carbonates

Nb(OR)4[OC(0)OR] (R = Me, Et, allyl) compounds have been synthesized by the reaction of dimeric alkoxo complexes [Nb(OR)s]2 with C02. The kinetics of the reaction has shown that the monomer in equilibrium with the dimer is the species that reacts with C02. The resulting compounds are monomeric with a -O,O-bonded hemicarbonate group. The C02 uptake is reversible. The hemicarbonates react with the parent alcohol to afford the relevant organic carbonate (RO)2CO with a turnover number (TON) of >2.