Knowledge Bank

Both the anion and dianion of $CO2$ are formed upon cocondensation of one of the alkali metal atoms (Li, K or Cs) and carbon dioxide in excess inert gas matrices. All three intra-ionic infrared active modes of CO3 have been identified. Isotopic studies of enriched carbon-13 and oxygen-18, $CO2$, have been carried out in order to determine the structure of the radical anion, $CO2-$. The effect of the size and the electropositivity of the metal atom on the $CO2-$ angle is studied. Reaction of alkali metal molecules and/or two alkali metal atoms with $CO2$ result in the formation of $M+\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}CO2-$ (where M = Li, K or Cs). Band assignment have been made for the three fundamentals of the dianion, $CO2$. Normal coordinate analyses have been carried out using all the measured frequencies for the various isotopomers of $CO2-$ and $CO2=$.