Mechanistic aspects of CO2 activation mediated by phenyl yttrium cation: A combined experimental/theoretical study

- The thermal reactions of [Y(C6D5)]+ with carbon dioxide have been investigated.
- The process proceeds by migratory insertion under CC bond formation.
- Direct O-atom transfer is not accessible from encounter complexes.
- CO can be eliminated from intermediates, which are formed in the course of insertion.

The thermal reactions of the per-deuterated yttrium phenyl cation with carbon dioxide have been investigated experimentally by using electrospray-ionization mass spectrometry and computationally by means of density functional theory. The process proceeds by migratory insertion under CC bond formation followed, to some extent, by decarbonylation. Labeling experiments with C18O2 confirm the origin of the oxygen incorporated in both productions. With regard to the mechanisms, the calculations reveal that the benzoate salt of yttrium corresponds to the most stable isomer. While extrusion of CO starting from this ion, or from two isomeric encounter complexes, is hampered by kinetic barriers, decarbonylation is accessible under thermal conditions from other intermediates which are generated after insertion of CO2 into the YC bond of [YC6D5]+.

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