Reactions of Laser-Ablated U and Th with CO2: Neon Matrix Infrared Spectra and Density Functional Calculations of OUCO, OThCO, and Other Products

Laser-ablated U and Th atoms react with CO 2 to give OUCO (1806.9, 823.2 cm - 1 ) and OThCO (1778.4 cm - 1 ) as major products, which are identified by isotopic substitution ( 13 CO 2, C 18 O 2 and 12 CO 2 + 13 CO 2, C 16 O 18 O + C 18 O 2 mixtures), doping with CCl 4 as an electron trap, and comparison with frequencies from density functional calculations. The insertion reaction is spontaneous as these bands increase on annealing the neon matrix from 4 to 6 K. Further reaction of OAnCO (An = Th, U) with another CO 2 molecule gives the O 2 An(CO) 2 product, although much more so with uranium than thorium. Reaction of the metal cations with CO 2 produces OUCO + (2073.0, 881.2 cm - 1 ) and OThCO + (2009.9, 896.4 cm - 1 ) with higher yield in thorium experiments. The O 2 An(CO) 2 - anions are observed for both metals again with higher yield in uranium investigations.