Thermodynamic properties of molecular borane amines and the [BH4-][NH4+] salt for chemical hydrogen storage systems from ab initio electronic structure theory
Thermodynamic properties of molecular borane amines and the [BH4-][NH4+] salt for chemical hydrogen storage systems from ab initio electronic structure theory
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DOI：
10.1021/jp0445627
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发表时间：
2005-06-16
影响因子：
2.9
通讯作者：
Gutowski, M
中科院分区：
文献类型：
--
作者：
Dixon, DA;Gutowski, M
硼烷胺 BH3NH3、BH2NH2 和 HBNH、四面体 BH4- 和 BN 分子的形成热已使用从头算分子轨道理论计算。采用单激发和双激发以及微扰三元组 (CCSD(T)) 的耦合簇计算来计算总价电子能量。使用相关一致的基组，通过增强的四重 zeta，外推到完整的基组极限。以附加方式包含核/价、标量相对论和自旋轨道校正来预测原子化能量。几何形状在 CCSD(T) 级别上计算，直到至少 aug-cc-pVTZ，频率在 CCSD(T)/aug-cc-pVDZ 级别上计算。气相 0 K 时的生成热（单位为 kcal/mol）为 Delta H-f(BH3NH3) = -9.1、Delta H-f(BH2NH2) = -15.9、Delta Hf(BHNH) = 13.6、Delta H-f(BN) = 146.4 和 Delta H-f (BH4-) = -11.6。报告的 Delta H-f(BN) 实验值显然是错误的。盐[BH4-][NH4+](s)的形成节拍已通过使用晶格能的经验表达式和计算的两个组分离子的形成热来估计。计算表明BH3NH3(g)和[BH4-][NH4+](S)都可以作为良好的储氢系统，在轻微放热过程中释放H-2。 BH3 的氢化物亲和力计算为 72.2 kcal/mol，与 298 K 下的实验值 74.2 +/- 2.8 kcal/mol 非常吻合。
The heats of formation for the borane amines BH3NH3, BH2NH2, and HBNH, tetrahedral BH4-, and the BN molecule have been calculated by using ab initio molecular orbital theory. Coupled cluster calculations with single and double excitations and perturbative triples (CCSD(T)) were employed for the total valence electronic energies. Correlation consistent basis sets were used, up through the augmented quadruple-zeta, to extrapolate to the complete basis set limit. Core/valence, scalar relativistic, and spin-orbit corrections were included in an additive fashion to predict the atomization energies. Geometries were calculated at the CCSD(T) level up through at least aug-cc-pVTZ and frequencies were calculated at the CCSD(T)/aug-cc-pVDZ level. The heats of formation (in kcal/mol) at 0 K in the gas phase are Delta H-f(BH3NH3) = -9.1, Delta H-f(BH2NH2) = -15.9, Delta Hf(BHNH) = 13.6, Delta H-f(BN) = 146.4, and Delta H-f (BH4-) = -11.6. The reported experimental value for Delta H-f(BN) is clearly in error. The beat of formation of the salt [BH4-][NH4+](s) has been estimated by using an empirical expression for the lattice energy and the calculated heats of formation of the two component ions. The calculations show that both BH3NH3(g) and [BH4-][NH4+](S) can serve as good hydrogen storage systems which release H-2 in a slightly exothermic process. The hydride affinity of BH3 is calculated to be 72.2 kcal/ mol, in excellent agreement with the experimental value at 298 K of 74.2 +/- 2.8 kcal/mol.