Activation of CO2coordinated to a Cr atom

The SCF-CI calculation gives the ‘end-on’ and ‘η2(O, O)’ coordination modes lowest in energy. The septet electron distributions show Cr+CO- 2, where the transferred (d or s) electron is localized at the carbon atom, providing an active site. The uncoordinated terminal oxygen atom offers a reinforced Lewis basic site in the quintet ‘side-on’ coordination.