【摘要】 在MP2/aug-cc-pVDZ理论水平上对一系列卤键复合物R-C≡N...BrY(R=F,Cl,Br,C≡CH,CH==CH2,CH3,C2H5;Y=F,Cl,Br)进行了系统的理论研究,采用量子化学从头算、电子密度拓扑分析方法,从分子静电势、复合物的稳定构型、振动频率、电子密度拓扑性质等方面,探讨了卤键作用的本质和性质特征.研究表明,RCN与BrY之间形成n型卤键,属于闭壳层静电相互作用.复合物与单体相比,电子受体Br-Y键的键长增加,振动频率红移.氰化物上取代基的诱导效应对复合物的几何构型、卤键强度、电子密度拓扑性质和原子积分性质等都产生显著影响.分子静电势与卤键强度、键鞍点处电子密度拓扑参数值(ρ(rc),▽2ρ(rc),Gc,Hc,-Gc/Vc)等密切相关.在卤键复合物形成过程中,电荷从RCN向BrY转移,BrY总积分净电荷减小,溴原子能量降低,溴原子偶极矩和原子体积均变小.更多还原

【Abstract】 A systematic theoretical study of halogen-bonded complexes R-C≡N...BrY(R=F,Cl,Br,C≡CH,CH==CH2,CH3,C2H5;Y=F,Cl,Br) was performed at the MP2/aug-cc-pVDZ level of theory.The nature and characteristics of the halogen bonds were studied by ab initio calculations and the quantum theory of "atoms in molecules"(QTAIM).Electrostatic potentials,equilibrium geometries,vibrational frequencies,and topological properties of the electron densities were investigated systematically.The results show that n-type halogen bonds are formed between RCN and BrY and that the studied halogen-bonding interactions are all "closed-shell" electrostatic interactions.Complex formation results in elongation of the Br-Y bond and a red-shift of its vibrational frequencies.The inductive effects of substituents on the cyanide significantly influence the complex geometries,strengths of the halogen-bonding interactions,topological properties of the electron densities,and atom basin integral properties.The electrostatic potentials correlate well with the strengths of the halogen-bonding interactions and the electron-density topological parameters(ρ(rc),▽2ρ(rc),Gc,Hc,-Gc/Vc).Charge transfers were observed from RCN to BrY in the formation of the halogen-bonded complexes.The energy,dipolar polarization,and atomic volume of the bromine atom all decrease upon complex formation.更多还原