Bond energy of ThN+: A guided ion beam and quantum chemical investigation of the reactions of thorium cation with N-2 and NO

Cox, RM; Kafle, A; Armentrout, PB; Peterson, KA

Armentrout, PB (reprint author), Univ Utah, Dept Chem, Salt Lake City, UT 84112 USA.



Kinetic-energy dependent reactions of Th+ with N-2 and NO are studied using a guided ion beam tandem mass spectrometer. The formation of ThO+ in the reaction of Th+ with NO is observed to be exothermic and barrierless with a reaction efficiency at low energies of 0.91 +/- 0.18. Formation of ThN+ in the reactions of Th+ with N-2 and NO is endothermic in both cases. The kinetic-energy dependent cross sections for formation of this product ion were evaluated to determine a 0 K bond dissociation energy (BDE) of D-0(Th+-N) = 6.51 +/- 0.08 eV, the first direct measurement of this BDE. Additionally, the reactions were explored by quantum chemical calculations, including a full Feller-Peterson-Dixon composite approach with correlation contributions up to CCSDTQ for ThN and ThN+, as well as more approximate CCSD(T) calculations where a semiempirical model was used to estimate spin-orbit energy contributions. The ThN+ BDE is found to be larger than those of the transition metal congeners, TiN+ along with estimated values for ZrN+ and HfN+, believed to be a result of the actinide contraction.

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