Ground-State Reversal by Matrix Interaction: Electronic States and Vibrational Frequencies of CUO in Solid Argon and Neon

Abstract

A 3Φ state is found for the CUO molecule (made by reaction of laser‐ablated U and CO) trapped in solid argon, in contrast to the 1Σ+ ground state in solid neon. The new electronic state results from the transfer of an electron from a U−C bonding orbital to a nonbonding 5f orbital of the U atom, thus decreasing the U−C stretching frequency significantly. Infrared spectroscopy and relativistic DFT calculations have been used to characterize these two low‐lying states of CUO.

Pentavalent lanthanide nitride-oxides: NPrO and NPrO−complexes with NPr triple bonds

“…Upon argon atom coordination, the Pr–N and Pr–O stretching modes red-shifted by 11.9 and 7.9 cm –1 , respectively. This result implies that the NPrO molecule trapped in a solid argon matrix may be regarded as a matrix-isolated NPrO(Ar) 6 complex, as in the case of the argon-coordinated CUO molecule 27(a),34. Similar calculations on neon complexes indicate that NPrO can also bind five or six neon atoms at the equatorial plane.…”

“…This result implies that the NPrO molecule trapped in a solid argon matrix may be regarded as a matrix-isolated NPrO(Ar) 6 complex, as in the case of the argon-coordinated CUO molecule. 27(a) , 34 Similar calculations on neon complexes indicate that NPrO can also bind five or six neon atoms at the equatorial plane. The NPrO(Ne) 5 complex has a slightly smaller binding energy (∼0.9 kcal mol –1 ), which might be partially responsible for the different matrix sites of NPrO observed.…”

The importance of spin-orbit coupling and electron correlation in the rationalization of the ground state of the CUO molecule

“…We first performed DFT calculations similar to the work of Bursten et al, 5,8,27 to see whether use of the more accurate relativistic approximation, ZORA, instead of the quasirelativistic Pauli approach would make any difference. This is not the case: the scalar results shown in Table II are consistent with the ones obtained by Andrews, giving a higher stabilization of the 1 ⌺ 0 ϩ states over the 3 ⌽ state of ⌬E ϭ12.6 kJ/mol.…”

A Fock space coupled cluster study on the electronic structure of the UO2, UO2+, U4+, and U5+ species

“…A particularly interesting aspect is the interaction of small actinide molecules with noble gas matrices. Laser ablation spectroscopy has been used by Andrews and co-workers to trap UO, UO 2 , and CUO in noble gas matrices 3,[6][7][8][9][10][11][12][13][14][15] and measure vibrational frequencies as a function of the matrix composition ͑Ne, Ar, Kr, Xe, or mixtures thereof͒. An intriguing feature of both CUO and UO 2 is the large redshift ͑about 130 cm −1 ͒ in the antisymmetric stretch found when replacing a neon matrix by an argon matrix.…”