对乙硼烷分子中“氢桥键”的重新认识

Reinspecting the"hydrogen-bridge bond"of diborane B_2H_6

为了弄清B_2H_6分子中氢桥键的本质,应用MP2/6-31++G(D,P)方法,分析并对比了C_2H_4,C_2H_6^(2+),B_2H_4^(2-)和B_2H_6四个分子的电子结构。结果显示,在某种程度上,B_2H_6分子中的氢桥键可以看成一个双中心双电子的离域π键(或者叫定域π键)电子云吸附2个带正电的质子构成。这种多中心多电子的离域键电子云吸附质子的现象被进一步推广到含有环形离域键的B_3H_5和B_4H_6分子中,并且得到了验证。本文得出的结论对正确理解氢桥键的本质有一定的促进作用。

The electronic structures of the four isoelectronic molecules（or ions） C2H4, C2H62＋, B2H42-, B2H6 were analysised and compared in order to have a thoroughly understanding of the hydrogen-bridge bond. The results show that, in a certain extent, the hydrogen-bridge bond of the B2H6 can be regarded as a 2-center 2-electron delocalized bond that inserted with two positive charged protons. The phenomenon that the electron cloud of delocalized bond inclining to accept positive charged proton was further confirmed through appling the conclusion to B3H5 and B4H6 molecules which has a ring-shape delocalized bond. The research of this paper will help chemist recognize the hydrogen-bridge bond more precisely All the results were obatined by the computational method at MP2/6-3l＋＋（D,P）level.