An infrared study of CO2 activation by holmium ions, Ho+ and HoO+

We report a combined experimental and computational study of carbon dioxide activation at gas-phase Ho+ and HoO+ centres. Infrared action spectra of Ho(CO2)(n)(+) and [HoO(CO2)(n)](+) ion-molecule complexes have been recorded in the spectral region 1700-2400 cm(-1) and assigned by comparison with simulated spectra of energetically low-lying structures determined by density functional theory. Little by way of activation is observed in Ho(CO2)(n)(+) complexes with CO2 binding end-on to the Ho+ ion. By contrast, all [HoO(CO2)(n)](+) complexes n >= 3 show unambiguous evidence for formation of a carbonate radical anion moiety, {CO3 center dot delta-}. The signature of this structure, a new vibrational band observed around 1840 cm(-1) for n = 3, continues to red-shift monotonically with each successive CO2 Eigand binding with net charge transfer from the Eigand rather than the metal centre.

Automated summary

In this study, carbon dioxide activation at gas-phase Ho+ and HoO+ centers was investigated through experimental and computational methods. The results showed that Ho(CO2)(n)(+) complexes with CO2 binding end-on to the Ho+ ion did not undergo significant activation, while [HoO(CO2)(n)](+) complexes with n >= 3 provided clear evidence for the formation of a carbonate radical anion.