• 中文核心期刊要目总览
  • 中国科技核心期刊
  • 中国科学引文数据库(CSCD)
  • 中国科技论文与引文数据库(CSTPCD)
  • 中国学术期刊文摘数据库(CSAD)
  • 中国学术期刊(网络版)(CNKI)
  • 中文科技期刊数据库
  • 万方数据知识服务平台
  • 中国超星期刊域出版平台
  • 国家科技学术期刊开放平台
  • 荷兰文摘与引文数据库(SCOPUS)
  • 日本科学技术振兴机构数据库(JST)

醌氢醌分子络合物内氢转移协同作用的量子化学研究

Cooperation Effects of Hydrogen Transfer In Quinhydrone Quantum Chemistry Study

  • 摘要: 本文用MNDO(RHF,UHF)方法计算了对苯醌和氢醌形成的分子络合物醌氨醌中的氢原子转移(双氢转移:H2Q+Q→Q+H2Q;单氢转移:H2Q+Q→2HQ),这些转移和电荷转移,生成热以及优化的转移中间态几何构型的关系,模型之一是:氢原子在平行的分子平面之间转移(pp);模型之二是:氢原子通过氢键在同一平面内转移(zz).单氢转移时(可能产生顺磁性),UHF计算出(zz)方式的势垒比(pp)方式的高一倍.EHF计算得出(pp)方式,在基态转移时的势垒比在激发态时高一倍.计算得出:(pp)方式转移时,醌和氢醌的二对氧原子的间距会协调地缩短,以配合氢原子的转移,而且,在基态作(pp)方式单氢原子转移的势垒比较小,这和晶态醌氢配在100°C以上出现由抗磁性向顺磁性转变的现象是一致的.

     

    Abstract: The transfer of hydrogen atoms between molecules in the molecular complexes quinhydrone (Q-H2Q) which consisted of benzoquinone(Q) and hydroquinone (H2Q), is studied with MNDO(RHF, UHF). The first model (pp) is the hydrogen atoms transfers take place between the two parallel molecular planes; the second model(zz) is the transfers being through the hydrogen bond from H2Q to Q which are keeping co-plane. The charge transfers, heat of formation and transientstate configurations are optimized for two processes:(A). 2H-transfer:Q-H2Q+Q→Q+H2Q, (B). 1H-transfer:H2Q+Q→2HQ (semiquinone, have diamagnetic→paramagnetic). The 1H-transfer potential barrier of (q) is 5.2eV(ground state) and 5.5eV (triplet); but for (pp), it is 2.5 and 3.0 respectively, the comparatively lower barrier is the fact that consistent with phenomenon that crystal quinhydrone from diamagnetic converted to paramagnetic when temperature above 100°. The barriers of 2H-transfer of (pp) in ground state are 5.3eV(90°) and 7.9eV(112°), but in excited state they are 3.0eV(112°, singlet) and 3.5eV(112°,triplet). The cooperation effects have been obtained by calculations; in (pp) model,when 1H-OR 2H-transfer from H2Q to Q, the distances between the oxygen atoms can harmoniously shortened, then it is profit to the hydrogen transfer.

     

/

返回文章
返回