%0 Journal Article %A Wang, Xuefeng %A Andrews, Lester %A Malmqvist, Per-Åke %A Roos, Björn O. %A Gonçalves, António P. %A C. L. Pereira, Cláudia %A Marçalo, Joaquim %A Godart, Claude %D 2010 %T Infrared Spectra and Quantum Chemical Calculations of the Uranium Carbide Molecules UC and CUC with Triple Bonds %U https://acs.figshare.com/articles/journal_contribution/Infrared_Spectra_and_Quantum_Chemical_Calculations_of_the_Uranium_Carbide_Molecules_UC_and_CUC_with_Triple_Bonds/2758405 %R 10.1021/ja102475t.s001 %2 https://acs.figshare.com/ndownloader/files/4451314 %K frequency ratio %K Triple BondsLaser evaporation %K CASPT 2 calculations %K 3Σ %K cm %K bond order %K CUC %K CUO %K 1.840 Å bond length %K 1.855 Å bond length %K Uranium Carbide Molecules UC %K molecule %K Quantum Chemical Calculations %X Laser evaporation of carbon-rich uranium/carbon alloys followed by atom reactions in a solid argon matrix and trapping at 8 K gives weak infrared absorptions for CUO at 852 and 804 cm−1. A new band at 827 cm−1 becomes a doublet with mixed carbon 12 and 13 isotopes and exhibits the 1.0381 isotopic frequency ratio, which is appropriate for the UC diatomic molecule, and another new band at 891 cm−1 gives a three-band mixed isotopic spectrum with the 1.0366 isotopic frequency ratio, which is characteristic of the linear CUC molecule. CASPT2 calculations with dynamical correlation find the CUC ground state as linear 3Σu+ with 1.840 Å bond length and molecular orbital occupancies for an effective bond order of 2.83. Similar calculations with spin-orbit coupling show that the UC diatomic molecule has a quintet (Λ = 5, Ω = 3) ground state, a similar 1.855 Å bond length, and a fully developed triple bond of 2.82 effective bond order. %I ACS Publications