Spectroscopic and Theoretical Studies on the Reactions of Laser-Ablated Tantalum with Carbon Dioxide

Using matrix-isolation infrared spectroscopy and DFT calculations, the reactions between 532 nm pulsed laser-ablated Ta and CO<INF>2</INF> in argon gas ambient have been investigated. The major reaction products trapped in solid argon were found to be neutral OTaCO and O<INF>2</INF>Ta(CO)<INF>2</INF> the anions OTaCO^- and O<INF>2</INF>Ta(CO)<INF>2</INF>^-. The observed absorption bands of the reaction products were identified by isotopic substitution and reproduced well by DFT calculations of vibrational fundamentals. Upon irradiation with a pulsed laser at 355 nm, the neutral OTaCO and O<INF>2</INF>Ta(CO)<INF>2</INF> were enhanced while O<INF>2</INF>Ta(CO)<INF>2</INF>^- and C<INF>2</INF>O<INF>4</INF>^- anions disappeared in the measured IR spectra. The potential energy surfaces of the interactions of Ta with CO<INF>2</INF> and CO<INF>2</INF>^- were calculated, and the insertion of Ta into CO<INF>2</INF> was suggested to proceed via electron transfer from Ta to CO<INF>2</INF>, in which CO<INF>2</INF>^- formation plays an important role in the activation of inert CO<INF>2</INF> molecules.