Quantum-chemical Study on the Structures and Properties of Uracil-BX_3 (X = F,Cl) Complexes  

作　　者：ZHANG Shi-Guo LI Hong YANG Pin 

机构地区：[1]Department of Chemistry and Chemical Engineering, Institute ofMaterial Chemistry, Binzhou University, Binzhou 256603, China [2]Key Laboratory. of Chemical Biology and Molecular Engineering of Minist~ ofEducation, Institute of Molecular Science Shanxi University, Taiyuan 030006, China

出　　处：《Chinese Journal of Structural Chemistry》2006年第8期947-956,共10页结构化学（英文）

基　　金：This work was supported by the National Natural Science Foundation of China (No. 20171031)

摘　　要：For the uracil-BX3 （X = F, Cl） systems, geometries and binding energies have been calculated by using the Lee-Young-Parr correlation functionals （B3LYP） method of density functional theory （DFT） and the second-order Moller-Plesset （MP2） method of ab initio at the 6- 311 ＋G^＊ or 6-311 ＋＋G^＊ basis set. Four isomers were found for each system, and then the single-point energy evaluations were performed using the larger basis sets of （6-311 ＋G（2df, p） and aug-cc-pVDZ with DFF method. In the most stable isomer of uracil-BF3 or uracil-BCl3, the boron atom of BX3 （X = F, Cl） connects to the carbonyl oxygen O7 of uracil with a stabilization energy of -46.56 or -31.10 kJ/mol at the B3LYP/6-31 1＋G^＊ level （BSSE corrected）. The analyses for combining interaction between BX3 and uracil with the atom-in-molecule theory （AIM） and natural bond orbital method （NBO） have been performed. The results indicate that all isomers were formed with σ-p type interactions between uracil and BX3, in which the carbonyl oxygen offers its lone pair electrons to the empty p orbital of boron atom and the concomitances of charge transfer from uracil to BX3 occur. Moreover, there exists one or two hydrogen bonds in most isomers of uracil-BX3 system and these hydrogen bonds contribute to the stability of the complex systems. Frequency analysis suggests that the stretching vibration of BX3 undergoes a red shift in complexes. Uracil-BF3 complex is more stable than uracil-BCl3 although the distance of B-O is shorter in the latter. Besides, the conversion mechanisms between different isomers of uracil-BF3 have been obtained.For the uracil-BX3 （X = F, Cl） systems, geometries and binding energies have been calculated by using the Lee-Young-Parr correlation functionals （B3LYP） method of density functional theory （DFT） and the second-order Moller-Plesset （MP2） method of ab initio at the 6- 311 ＋G^＊ or 6-311 ＋＋G^＊ basis set. Four isomers were found for each system, and then the single-point energy evaluations were performed using the larger basis sets of （6-311 ＋G（2df, p） and aug-cc-pVDZ with DFF method. In the most stable isomer of uracil-BF3 or uracil-BCl3, the boron atom of BX3 （X = F, Cl） connects to the carbonyl oxygen O7 of uracil with a stabilization energy of -46.56 or -31.10 kJ/mol at the B3LYP/6-31 1＋G^＊ level （BSSE corrected）. The analyses for combining interaction between BX3 and uracil with the atom-in-molecule theory （AIM） and natural bond orbital method （NBO） have been performed. The results indicate that all isomers were formed with σ-p type interactions between uracil and BX3, in which the carbonyl oxygen offers its lone pair electrons to the empty p orbital of boron atom and the concomitances of charge transfer from uracil to BX3 occur. Moreover, there exists one or two hydrogen bonds in most isomers of uracil-BX3 system and these hydrogen bonds contribute to the stability of the complex systems. Frequency analysis suggests that the stretching vibration of BX3 undergoes a red shift in complexes. Uracil-BF3 complex is more stable than uracil-BCl3 although the distance of B-O is shorter in the latter. Besides, the conversion mechanisms between different isomers of uracil-BF3 have been obtained.

关 键 词：B3LYP MP2 intermolecular interaction uracil-BF3 complex uracil-BCl3 complex 

分 类 号：O641.4[理学—物理化学]