Cox Richard M, Kafle Arjun, Armentrout P B, Peterson Kirk A
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, USA.
Department of Chemistry, Washington State University, Pullman, Washington 99164-4630, USA.
J Chem Phys. 2019 Jul 21;151(3):034304. doi: 10.1063/1.5111534.
Kinetic-energy dependent reactions of Th with N 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 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(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.
使用导向离子束串联质谱仪研究了钍（Th）与氮（N）和一氧化氮（NO）的动能相关反应。观察到在钍与一氧化氮的反应中氧化钍（ThO）的形成是放热且无势垒的，在低能量下反应效率为0.91±0.18。在钍与氮以及钍与一氧化氮的反应中，氮化钍（ThN）的形成在两种情况下都是吸热的。评估了该产物离子形成的动能相关截面，以确定0K时D(Th-N)=6.51±0.08电子伏特的键解离能（BDE），这是对该BDE的首次直接测量。此外，通过量子化学计算对反应进行了探索，包括对ThN和ThN采用完整的费勒 - 彼得森 - 迪克森复合方法并包含直至CCSDTQ的相关贡献，以及使用半经验模型估计自旋 - 轨道能量贡献的更近似的CCSD(T)计算。发现ThN的BDE大于过渡金属同系物TiN以及ZrN和HfN的估计值，这被认为是锕系收缩的结果。
