胞嘧啶-BH_3复合物构型与性质的量子化学研究

对胞嘧啶-BH3复合物分别用B3LYP/6-31G和MP2/6-31G进行理论计算以预测该复合物的构型及稳定化能, 得到了5种构型。对各构型进行了振动频率分析和自然键轨道分析。结果表明, B与N和O直接相连的构型比较稳定, 其稳定化能为137.4和120.0 kJ/mol (MP2/6-31G)。其余的构型靠π-p作用而形成, 其稳定性较前两者弱。各构型的稳定化能与电荷转移量有良好的相关性。复合物的形成, 使其红外光谱均有不同程度的红移, 幅度与复合物的稳定性相关。

Quantum Chemistry Study of the Structures and Properties for Cytosine-BH3 Complexes

The geometries and combination energies are predicated at the B3LYP/6-31G and MP2/6-31G levels for the cytosine-BH3 complexes and 5 geometries have been obtained. The vibrational and natural bond orbital analy- ses were carried out, indicating two configurations with the boron atom directly combining to N or O are relatively stable with the combination energies of 137.4 and 120.0 kJ/mol, respectively (MP2/6-31G). The stabilities of the remainders formed with -p interaction are weaker, and those of all conformers are relative to the charge transference shifts. The calculated results show that when the complex formed, their IR spectra move to the red side and the frequency shifts are relative to the stabilities of the complexes.