Carbon dioxide exchange reactions involving early transition-metal NN-dimethylcarbamato compounds: reversible insertion of carbon dioxide into transition-metal–nitrogen σ-bonds

Abstract

Transition-metal NN-dimethylcarbamato compounds ML*_n, (where M = Ti, Zr and n= 4; M = Nb, Ta and n= 5), W₂L*₆ and W(NMe₂)₃L*₃, (L*= O₂¹³CNMe₂), react with ¹²CO₂ to give ML_n, W₂L₆ and W(NMe₂)₃L₃, where (L = O₂¹²CNMe₂), with an energy of activation ranging from ca. 54 ± 8kJ mol^–1 for ZrL₄ to ca. 96kJ mol^–1 for W(NMe₂)₃L₃; mixtures of ML_n and ML*_n scramble CO₂ in the absence of an applied CO₂ atmosphere.