σ-Holes, π-holes and electrostatically-driven interactions
σ-Holes, π-holes and electrostatically-driven interactions
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DOI：
10.1007/s00894-011-1089-1
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发表时间：
2012-02-01
影响因子：
2.2
通讯作者：
Politzer, Peter
中科院分区：
文献类型：
--
作者：
Murray, Jane S.;Lane, Pat;Politzer, Peter
正空穴是垂直于分子结构的一部分的具有正静电势的区域。它与sigma空穴相对应，后者沿着共价键延伸到原子。西格玛空穴和π空穴都变得更有正电(a)在元素周期表的给定基团中从较轻的原子向较重的原子移动，(b)分子的其余部分更吸电子。正的西格玛洞和π洞可以以高度定向的方式与负的位点相互作用，例如，路易斯碱基的孤对。本文采用MP2、M06-2X和B3PW91程序对13个含pi空穴分子与HCN和NH3的氮孤对的配合物进行了计算表征。虽然静电相互作用是pi-hole键的主要驱动力，但发现从弱非共价到相当强的梯度，可能有一定程度的配位共价的迹象。
A positive pi-hole is a region of positive electrostatic potential that is perpendicular to a portion of a molecular framework. It is the counterpart of a sigma-hole, which is along the extension of a covalent bond to an atom. Both sigma-holes and pi-holes become more positive (a) in going from the lighter to the heavier atoms in a given Group of the periodic table, and (b) as the remainder of the molecule is more electron-withdrawing. Positive sigma- and pi-holes can interact in a highly directional manner with negative sites, e.g., the lone pairs of Lewis bases. In this work, the complexes of 13 pi-hole-containing molecules with the nitrogen lone pairs of HCN and NH3 have been characterized computationally using the MP2, M06-2X and B3PW91 procedures. While the electrostatic interaction is a major driving force in pi-hole bonding, a gradation is found from weakly noncovalent to considerably stronger with possible indications of some degree of coordinate covalency.