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用量子化学从头算方法在MP2/6-311++G(d,p)与MP2/6-311++G(2df,2p)两个理论级别上研究了双接触弯曲氢键Y…H2CZ(Z=O,S,Se)和Y…H2CZ2(Z=F,Cl,Br)(Y=Cl-,Br-).计算表明,在这些复合物中都存在两个等价的Y…H—C蓝移氢键;相互作用能和蓝移都比较大,每个Y…H—C氢键的能量为15～27kJ/mol,CH键长变化为-0.1～-0.5pm,CH伸缩振动频率位移为30～80cm-1.自然键轨道分析表明,3个因素导致了这些蓝移氢键的形成:(1)存在较大的重杂化;(2)弯曲的氢键构型使得分子间直接超共轭相互作用比较小,而存在相当的分子间间接超共轭相互作用;(3)质子给体的分子内超共轭相互作用较大地减小.电子密度拓扑性质的研究表明,在这些氢键复合物中都存在3个分子间临界点:在接受体原子Y与每个H原子之间存在一个键临界点,也存在相应的键径和原子间界面;在YHCH四边形内部存在一个环临界点.因此这些分子间相互作用可以严格地看作氢键.
Quantum chemical ab initio method has been used to study two-contact curved hydrogen bonds Y ... H2CZ (2d, 2p, 2p) at MP2 / 6-311 ++ G (d, p) and MP2 / 6-311 ++ G Z = O, S, Se) and Y ... H2CZ2 (Y = Cl-, Br-). The calculations show that there are two equivalent Y ... H- C blue shift hydrogen bond; interaction energy and blue shift are relatively large, each Y ... H-C hydrogen bond energy is 15 ~ 27kJ / mol, CH bond length change -0.1 ~ -0.5pm, CH stretching vibration frequency And the displacement is 30 ~ 80cm-1. The analysis of natural bond orbital shows that three factors lead to the formation of these blue-shifted hydrogen bonds: (1) there is a large heavy hybridization; (2) the curved hydrogen bond configuration makes the intermolecular Direct superconjugation interaction is relatively small, while there is a considerable indirect interconjugation interaction between molecules; (3) the intramolecular hyperconjugation interaction of proton donors decreases greatly.Study on the topological properties of electron density There are three intermolecular critical points in these hydrogen bond complexes: there exists a critical point between the acceptor atom Y and each H atom, and there is also a corresponding bond diameter and inter-atom interface; there is one inside the YHCH tetragon Ring critical point. So these molecules interact To strictly as hydrogen bonds.