【作者】 纪宏波；

【导师】 黎安勇；

【作者基本信息】 西南大学 ， 物理化学， 2010， 硕士

【摘要】 本课题运用量子化学从头算方法,研究了以BH2NH2,HBeH和HZnH作为质子接受体,以HArF、HKrF、HCF3、HCC13、HF、HC1、HCOF和HCOC1等小分子作为质子给予体所形成的双氢键M-H.-.H-X的结构与本质。用分子中原子理论(AIM)研究了单体与复合物的电子密度拓扑性质,用自然键轨道(NBO, Natural bond orbital)方法研究了双氢键形成时单体间的分子轨道之间的相互作用以及单体内原子轨道、分子轨道以及化学键的变化,从理论上解释了双氢键的形成导致的单体分子结构的变化以及特征振动频率的位移,并用ChelpG方法模拟质子接受体电荷产生的静电场,研究静电作用对双氢键的贡献。本文主要包括以下三个部分。1、运用量子化学从头算方法,研究了NH2BH2作为质子受体与HCF3、HCC13、HF、HC1、HCOF和HCOC1作为质子给体形成的双氢键B-H…H-X(X=F、C1、C)。计算结果表明,在所有复合物中,BH键键长增长,伸缩振动频率红移；在HF与HCl的复合物中,XH键键长增长,伸缩振动频率红移；在其他复合物中,XH键键长缩短,伸缩振动频率蓝移。在每个体系中,还存在传统氢键N-H…Y(Y=F,C1,O)。分析表明,在这些复合物中双氢键是以静电作用为主,振动频率红移蓝移的变化是因为分子间与分子内电子密度转移引起的,可以用Alabugin的超共轭和重杂化理论进行解释,同时必须考虑分子内超共轭作用。2、在MP2(full)/6-311++G(2d,2p)级别下对HBeH与HRgF(Rg=Ar,Kr)形成的双氢键进行了理论研究。计算结果表明,所有单体与复合物均为线性构型；相互作用能较大。静电作用与分子间超共轭σ(BeH)→6*(HRg)产生的电荷转移共同导致质子给体的HRg键削弱与频率红移,其中静电相互作用更重要；质子给体的分子内超共轭n(F)→σ*(HRg)的调节作用削弱了电荷转移的影响。分子间超共轭也导致质子接受体BeH削弱因而键长增大与频率红移。3、在MP2(full)/6-311++G(2d,2p)级别下对XZnH(X=F,C1,Br)与HKrF形成的双氢键进行了理论研究。计算结果表明,所有单体与复合物均为线性构型。分子间超共轭σ(ZnH)→σ*(HKr)产生的电荷转移导致质子给体的HKr键削弱与频率红移；质子给体的分子内超共轭n(F)→6*(HKr)的调节作用削弱了电荷转移的影响。分子间超共轭也导致质子接受体ZnH削弱因而键长增大与频率红移。更多还原

【Abstract】 In this paper, Ab initio quantum chemistry methed was employed to investigate the dihydrogen bonds B-H…H-X(X=C,F,Cl, Ar, Kr) between (NH2BH2,HBeH,HZnH) as the proton acceptors and small molecules (HArF, HKrF, HF, HCl, CHF3,HCC13, HCOCl and HCOF) as the proton donors. We used the AIM theory to study the topological proporties of electron density of the monomers and complexes, and used the NBO (natural bond orbital) method to study interactions between molecular orbitals of the monomers, and the changes of the atomical orbitals, molecular orbitals and chemical bonds in a monomer upon formation of the dihydrogen bonds. We also used the CHelpG method to simulate the electrostatic field of the proton acceptor, and studied the contribution of the electrostatic interaction to the formation of dihydrogen bonds.1.Ab initio quantum chemistry method was employed to investigate the dihydrogen bonds B-H…H-X(X=C,F,Cl) between NH2BH2 as proton donor and small molecules (HF, HCl, CHF3,HCCl3,HCOCl and HCOF) as proton acceptors. Calculation indicated that in all of the systems the formation of dihydrogen bond leads to red shifts of BH bonds, red shifts of H-F and H-Cl bonds in the compounds of NH2BH2…HF and NH2BH2-HCl, and blue shifts of H-C in the compounds of NH2BH2…CHF3, NH2BH2-HCC13,NH2BH2…HCOF and NH2BH2…HCOC1. There are also tranditional hydrogen bonds N-H…Y(Y=C1, F, O) in these systems. The results of AIM and NBO analysis showed that electrostatic interaction plays an important role in dihydrogen bonds and tranditional hydrogen bonds in all the systems. The red and blue shifts of vibration frequency were caused by intermolecular electron dentisy transfer, and the intramolecules hyperconjugation must be considered.2.Ab initio quantum chemistry methods were applied to investigate the dihydrogen bonds HBeH...HRgF(Rg=Ar,Kr) at the MP2(full)/6-311++G(2d,2p) level. The results show that all the monomers and complexes are linear, and the interaction energies are large.Electrostatic interaction and electron density transfer caused by intermolecular hyperconjugationσ(BeH)→σ*(HRg) weaken the HRg bond of the proton donor and cause its frequency red shift, electrostatic interaction is predominant; the intramolecular hyperconjugation n(F)→σ*(HRg) in the proton donor weakens the affect of charge transfer. Meanwhile, the intermolecular hyperconjugation causes the BeH bond weakening and elongating with concomitant frequency red shift.3.Ab initio quantum chemistry methods were applied to investigate the dihydrogen bonds XZnH...HKrF(X= F,Cl,Br) at the MP2(full)/6-311++G(2d,2p) level. The results show that all the monomers and complexes are linear. the intermolecular hyperconjugationσ(ZnH)→σ*(HRg) causes the ZnH bond weakening and elongating with concomitant frequency red shift. Meanwhile, electron density transfer caused by intermolecular hyperconjugationσ(ZnH)→σ*(HRg) weaken the HRg bond of the proton donor and cause its frequency red shift. the intramolecular hyperconjugation n(F)→σ*(HRg) in the proton donor weakens the affect of charge transfer.更多还原