吡咯-HCN体系在气相及溶液中相互作用的理论研究

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Bemardi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-19.30 kJ·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 superthe H - N vibration mode. The solvent effect is obvious when dielectric constant s is within 1.5 ～ 30. 0 and is weak when ε exceeds 30.0.