高等学校化学学报

高等学校化学学报 ›› 2000, Vol. 21 ›› Issue (4): 596.

• 论文 • 上一篇    下一篇

3,4-二硫方酸芳香性和气相酸性的理论研究

周立新, 莽朝永, 黄尊行   

  1. 福州大学化学系, 福州 350002
  • 收稿日期:1999-04-02 出版日期:2000-04-24 发布日期:2000-04-24
  • 通讯作者: 周立新(1954年出生),男,博士,副教授,从事量子化学研究.
  • 基金资助:

    福建省自然科学基金;福建省高等学校科学基金

Theoretical Studies of the Gas-phase Acidity and Aromaticity of 3,4-Dithiosquaric Acid

ZHOU Li-Xin, MANG Chao-Yong, HUANG Zun-Xing   

  1. Department of Chemistry, Fuzhou University, Fuzhou 350002, China
  • Received:1999-04-02 Online:2000-04-24 Published:2000-04-24

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被引次数

3

摘要： 在RHF/6-311G**,RHF/6-311+G**和B3LYP/6-311+G**水平优化得到3,4-二硫方酸(3,4-二巯基-3-环丁烯-1,2-二酮)三种平面构象异构体的平衡几何构型.用MP2(Full)/6-311G**//RHF/6-311G**方法计算单点能量,发现ZZ型异构体是能量最低构象,且ZZ和ZE型能量非常接近.用优化的最稳定构象ZZ型异构体在RHF/6-311G**//RHF/6-311G**,RHF/6-311G**//RHF/6-311G**,MP2(Full)/6-311G**//RHF/6-311G**和B3LYP/6-311G**//B3LYP/6-311G**水平计算其气相酸性(ΔG0)和同键反应芳香性稳定化能(HASE).用基团加和法(Group Increment Approach)在RHF/6-311G**//RHF/6-311G**和B3LYP/6-311G**//B3LYP/6-311G**水平计算其磁化率增量(Λ).计算结果表明,标题化合物的同键反应芳香性稳定化能和磁化率增量均为负值,表明它具有芳香性,实现了标题化合物芳香性的几何、能量和磁性的判定.

关键词: 3, 4-二硫方酸, 从头算, 密度泛函, 芳香性, 气相酸性

Abstract: The conformation, aromaticity and gas phase acidity(free energy of deprotonation, ΔG0) of 3,4-dithiosquaric acid(3,4 dimercapto-3-cyclobutene 1,2-dione) were calculated at the SCF and MP2 and B3LYP levels using 6-311G(d,p) and 6-311+G(d,p) basis sets. The global minimum found on the potential energy surface of 3,4-dithiosquaric acid presents a planar conformation. The ZZisomer was found to be the most stable of the three planar conformers. The aromatic stabilization energy(ASE) and magnetic susceptibility exaltation( Λ ) were also computed by using the homodesmotic reaction and RHF-CSGT(Continues Set of Gauge Transformations) and RHF-IGAIM(a slight variation on CSGT) and B3LYP-CSGT(IGAIM) methods at the 6-311+G(d,p) level. The calculated ASEand Λ were negative values, indicating that 3,4-dithiosqaric acid is aromatic. Thus the titled compound fulfilled the geometrical, energetic and magnetic criteria of aromaticity. The most reliable theoretical gas-phase acidity are ΔG1,298K0 = 1295.4 kJ/mol and ΔG2,298K0 =1691.2 kJ/mol.

Key words: 3,4-Dithiosquaric acid, Ab initio, Density functional theory(DFT), Aromaticity, Gas-phase acidity

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