Studies of carbon monoxide activation with atomic lithium: IR spectra of LiCO, LiOC, LiC 2O 2 and Li 2C 2O 2 in cryogenic matrices

Abstract

Atomic lithium has been shown to react with carbon monoxide to form two geometric isomers, LiOC and LiCO. Each of these isomers reacts with a second molecule of carbon monoxide to form specific geometric isomers of LiC 2O 2. The LiOC isomer preferentially adds a second carbon monoxide to form LiC 2O 2 with a strong carboncarbon bond. The LiCO isomer adds a second carbon monoxide to form LiC 2O 2 with the two carbon monoxide molecules only weakly interacting. Further reaction of the form with a strong carboncarbon bond with atomic lithium produces the final product, lithium acetylenediolate, LiOCCOLi, a salt of the hypothetical oxy-acid, H 2C 2O 2. Two geometric forms of Li 2C 2O 2 are also produced. It is suggested that the less stable form has symmetrical bridging lithiums and that the most stable and final product involves interaction of lithiums with the terminal oxygens. Infrared frequencies have been assigned to the various species and are listed in the accompanying tables. Lithium-7, oxygen-18 and carbon-13 isotopic shifts have also been measured.