Stabilizing Otherwise Unstable Anions with Halogen Bonding

被引:21
作者
Zhang, Xinxing [1 ,2 ,3 ]
Liu, Gaoxiang [1 ]
Ciborowski, Sandra [1 ]
Bowen, Kit [1 ]
机构
[1] Johns Hopkins Univ, Dept Chem, 3400 N Charles St, Baltimore, MD 21218 USA
[2] CALTECH, Noyes Lab Chem Phys, Pasadena, CA 91125 USA
[3] CALTECH, Beckman Inst, Pasadena, CA 91125 USA
基金
美国国家科学基金会;
关键词
anions; density functional theory; halogen bonding; hydrogen bonding; photoelectron spectroscopy; PHOTOELECTRON-SPECTROSCOPY; WATER-MOLECULES; COMPLEXES; TRIMETHYLAMINE; DONORS; BR;
D O I
10.1002/anie.201705738
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Both hydrogen bonding (HB) and halogen bonding (XB) are essentially electrostatic interactions, but whereas hydrogen bonding has a well-documented record of stabilizing unstable anions, little is known about halogen bonding's ability to do so. Herein, we present a combined anion photoelectron spectroscopic and density functional theory study of the halogen bond-stabilization of the pyrazine (Pz) anion, an unstable anion in isolation due to its neutral counterpart having a negative electron affinity (EA). The halogen bond formed between the sigma-hole on bromobenzene (BrPh) and the lone pair(s) of Pz significantly lowers the energies of the Pz( BrPh)(1)(-) and Pz(BrPh)(2)(-) anions relative to the neutral molecule, resulting in the emergence of a positive EA for the neutral complexes. As seen through its charge distribution and electrostatic potential analyses, the negative charge on Pz(-) is diluted due to the XB. Thermodynamics reveals that the low temperature of the supersonic expansion plays a key role in forming these complexes.
引用
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页码:9897 / 9900
页数:4
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