Bessac Fabienne, Frenking Gernot
Laboratoire de Physique Quantique, Université Paul Sabatier, 118 Route de Narbonne, F-31062 Toulouse, France.
Inorg Chem. 2003 Dec 1;42(24):7990-4. doi: 10.1021/ic034141o.
Geometries and bond dissociation energies of the complexes Cl(3)B[bond]NH(3) and F(3)B[bond]NH(3) have been calculated using DFT (PW91) and ab initio methods at the MP2 and CCSD(T) levels using large basis sets. The calculations give a larger bond dissociation energy for Cl(3)B[bond]NH(3) than for F(3)B[bond]NH(3). Calculations of the deformation energy of the bonded fragments reveal that the distortion of BCl(3) and BF(3) from the equilibrium geometry to the pyramidal form in the complexes requires nearly the same energy. The higher Lewis acid strength of BCl(3) in X(3)B[bond]H(3) compared with BF(3) is an intrinsic property of the molecule. The energy partitioning analysis of Cl(3)B[bond]NH(3) and F(3)B[bond]NH(3) shows that the stronger bond in the former complex comes from enhanced covalent interactions between the Lewis acid and the Lewis base which can be explained with the energetically lower lying LUMO of BCl(3).
使用密度泛函理论（PW91）以及在MP2和CCSD（T）水平下的从头算方法，并采用大基组，计算了配合物Cl₃B═NH₃和F₃B═NH₃的几何结构和键解离能。计算结果表明，Cl₃B═NH₃的键解离能比F₃B═NH₃的更大。对键合片段变形能的计算表明，配合物中BCl₃和BF₃从平衡几何结构扭曲为金字塔形所需的能量几乎相同。与BF₃相比，X₃B═H₃中BCl₃更高的路易斯酸强度是该分子的固有性质。对Cl₃B═NH₃和F₃B═NH₃的能量划分分析表明，前一种配合物中更强的键来自路易斯酸和路易斯碱之间增强的共价相互作用，这可以用能量较低的BCl₃最低未占分子轨道来解释。
