摘要
用量子化学B3LYP方法在6-311G(d,p)水平上优化了吡咯-HCN氢键复合物,通过振动频率分析确定了两个吡咯-HCN体系稳定构型.为了得到更加精确的氢键作用能,采用相关一致基组aug-cc-pVDZ以及Boys和Bernardi的CP(counterpoise)校正方法消除基组重叠误差后得到C-H…π和N-H…N型复合物的氢键相互作用能.为了确定B3LYP方法计算的相互作用能的可靠性,在MP2/aug-cc-pVDZ水平计算了复合物的氢键相互作用能,结果分别为-25.10和-19.30kJ·mol-1.采用自然键轨道(NBO)分析考察了吡咯与HCN分子间轨道相互作用.以自洽场理论(SCRF)中的Onsager模型研究了不同极性溶剂对吡咯-氰化氢体系N-H…N型氢键几何构型,频率位移,电荷分布以及相对能量的影响.研究发现,当溶液的介电常数在1.5～30.0范围时,溶液作用十分显著,而当介电常数超过30.0以后,溶液作用已经达到了极限.
The hydrogen bonds between the HCN and pyrrole were subjected to density functional theory (DFT) calculations using 6-311G (d, p) basis set. The structures and vibrational frequencies of the hydrogen-bonding complexes were computed at the B3LYP/6-311G (d, p) level. To obtain the accurate binding energies, single-point calculations were performed at the B3LYP/aug-cc-pVDZ and MP2/aug-cc-pVDZ level, respectively. After BSSE (basic set superposition error) correction by the counterpoise method, the interaction energies of the complexes between HCN and pyrrole are -25. 10, -19. 30 kJ (.) mol(-1) at MP2 level, respectively. The calculations indicate that solvents enhance significantly the strength of hydrogen bond as shown by the decrease of the (NH)-H-... distance and cause appreciable red shift of the H - N vibration mode. The solvent effect is obvious when dielectric constant epsilon is within 1.5 `similar to 30.0 and is weak when v. exceeds 30.0.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2004年第11期1324-1328,共5页
Acta Physico-Chimica Sinica
基金
国家重点基础研究发展规划项目(G19990225)资助~~
