- Carbon dioxide activation by alkali metals. 2. Infrared spectra of M+CO2- and M22+CO22- in argon and nitrogen matrices
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The reactions of sodium, potassium, and cesium with carbon dioxide have been investigated in argon, nitrogen, and neat matrices. The spontaneous reduction of CO2 to the radical anion, CO2-, and dianion, CO22-, was successfully accomplished when potassium or cesium was used as the activating metal. M+CO2- (where M = Na, K, Cs) was found to have a rhombic ring structure of C2v symmetry where the metal atom is interacting equally with the two oxygen atoms. Two geometrical isomers of M22+CO22- (where M = K, Cs) have been isolated in argon and nitrogen matrices. Mixed C18O2/C16O2 studies suggest that one isomer has C2v symmetry where the two oxygens are in equivalent positions whereas the second isomer has Cs symmetry and nonequivalent oxygen atoms. It is suggested that M22+CO22- (C2v) is formed as a result of the reaction between the alkali-metal dimer M2 and CO2. Photolysis of the C2v form of the dimetal carbon dioxide dianion with the Nernst glower IR source causes its rearrangement to the Cs form. No bands associated with Na22+ CO22- have been detected in either argon or nitrogen matrices. Very small amounts of Na+CO2- were produced when Na was allowed to react with CO2 in inert-gas matrices. This reaction was enhanced by photolysis with a medium-pressure 100-W Hg lamp during or after deposition. By using the triatomic molecule approximation, one can determine bond angles equal to 131.1 and 126.9° for the CO2- valence-bond angle in K+CO2- (C2v) and Cs+CO2- (C2v) and bond angles equal to 125.9 and 123.1° for the CO22- valence-bond angle in K22+CO22- (C2v) and Cs22+CO22- (C2v).
- Kafafi, Zakya H.,Hauge, Robert H.,Billups, W. Edward,Margrave, John L.
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p. 177 - 183
(2008/10/08)
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