Gas Phase Properties of MX2 and MX4 (X = F, Cl) for M = Group 4, Group 14, Cerium, and Thorium.
Gas Phase Properties of MX2 and MX4 (X = F, Cl) for M = Group 4, Group 14, Cerium, and Thorium.
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DOI：
10.1021/acs.jpca.5b02544
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发表时间：
2015-05
期刊：
影响因子：
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通讯作者：
K. S. Thanthiriwatte;Monica Vasiliu;Samuel R Battey;Qing Lu;K. Peterson;L. Andrews;D. Dixon
中科院分区：
文献类型：
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作者：
K. S. Thanthiriwatte;Monica Vasiliu;Samuel R Battey;Qing Lu;K. Peterson;L. Andrews;D. Dixon
使用Feller-Peterson-狄克逊复合电子结构方法，基于耦合簇CCSD（T）计算，外推至完整基组极限，并进行额外校正（包括自旋轨道效应），预测了MX 4和MX 2（M =第4族、第14族、Ce和Th; X = F和Cl）的单重态和三重态的结构、振动频率和生成热。自旋轨道修正并不大，但需要将其纳入化学准确度±1 kcal/mol。计算了二卤化物的单重态-三重态分裂，除了Ti、Zr和Ce的二卤化物具有三重态基态外，所有化合物都具有单重态基态。计算的生成热与实验数据吻合得很好。我们的预测表明，实验生成热需要修改的一些四卤化物：TiF 4，HfF 4，PbF 4，PbCl 4，和ThCl 4以及一些二卤化物：GeF 2，SnF 2，PbF 2，TiF 2，和TiCl 2。计算的生成热用于预测各种热力学性质，包括平均M-F和M-Cl键离解能以及MX2 + X2 → MX4的反应能。预测了边缘反转势垒。计算结果表明，第14族四氟化物的能垒随着原子序数的增加而减小，第4族四氟化物的能垒为1.50 kcal/mol，CeF 4和ThF 4的能垒为1.25 kcal/mol.
Structures, vibrational frequencies, and heats of formation were predicted for MX4 and both singlet and triplet states of MX2 (M = group 4, group 14, Ce, and Th; X = F and Cl) using the Feller-Peterson-Dixon composite electronic structure approach based on coupled cluster CCSD(T) calculations extrapolated to the complete basis set limit with additional corrections including spin orbit effects. The spin-orbit corrections are not large but need to be included for chemical accuracy of ±1 kcal/mol. The singlet-triplet splittings were calculated for the dihalides and all compounds have singlet ground states except for the dihalides of Ti, Zr, and Ce which have triplet ground states. The calculated heats of formation are in good agreement with the available experimental data. Our predictions suggest that the experimental heats of formation need to be revised for a number of tetrahalides: TiF4, HfF4, PbF4, PbCl4, and ThCl4 as well as a number of dihalides: GeF2, SnF2, PbF2, TiF2, and TiCl2. The calculated heats of formation were used to predict various thermodynamic properties including average M-F and M-Cl bond dissociation energies and the reaction energies for MX2 + X2 → MX4. Edge inversion barriers were predicted. The calculated edge inversion barriers for the tetrafluorides show that the barriers for the group 14 tetrafluorides decrease with increasing atomic number, the group 4 barriers are ∼50 kcal/mol and CeF4 and ThF4 have inversion barriers of ∼25 kcal/mol.