Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, USA.
J Chem Phys. 2011 Mar 7;134(9):094315. doi: 10.1063/1.3562209.
When PH(3) is paired with NH(3), the two molecules are oriented such that the P and N atoms face one another directly, without the intermediacy of a H atom. Quantum calculations indicate that this attraction is due in part to the transfer of electron density from the lone pair of the N atom to the σ(∗) antibond of a P-H covalent bond. Unlike a H-bond, the pertinent hydrogen is oriented about 180° away from, instead of toward, the N, and the N lone pair overlaps with the lobe of the P-H σ(∗) orbital that is closest to the P. In contrast to halogen bonds, there is no requirement of a σ-hole of positive electrostatic potential on the P atom, nor is it necessary for the two interacting atoms to be of differing potential. In fact, the two atoms can be identical, as the global minimum of the PH(3) homodimer has the same structure, characterized by a P···P attraction. Natural bond orbital analysis, energy decomposition, and visualization of total electron density shifts reveal other similarities and differences between the three sorts of molecular interaction.
当 PH(3) 与 NH(3) 配对时，这两个分子的取向是 P 和 N 原子直接相对，而没有 H 原子的中介。量子计算表明，这种吸引力部分归因于 N 原子的孤对电子密度向 P-H 共价键的 σ(∗)反键的转移。与氢键不同，相关的氢原子的取向大约是 180°远离 N，而不是朝向 N，并且 N 的孤对电子与最靠近 P 的 P-H σ(∗)轨道的叶重叠。与卤键不同，P 原子上不需要正静电势能的 σ 空穴，也不需要两个相互作用的原子具有不同的势能。事实上，两个原子可以是相同的，因为 PH(3) 同二聚体的全局最小值具有相同的结构，其特征是 P···P 吸引力。自然键轨道分析、能量分解和总电子密度位移的可视化揭示了这三种分子相互作用之间的其他相似和不同之处。
