3,4-二硫方酸芳香性和气相酸性的理论研究  

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

作　　者：周立新[1] 莽朝永[1] 黄尊行[1] 

机构地区：[1]福州大学化学系,福州350002

出　　处：《高等学校化学学报》2000年第4期596-600,共5页Chemical Journal of Chinese Universities

基　　金：福建省自然科学基金;福建省高等学校科学基金

摘　　要：在 RHF/6-3 1 1 G* * ,RHF/6-3 1 1 +G* * 和 B3 LYP/6-3 1 1 +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) /6-3 1 1 +G* * //RHF/6-3 1 1 +G* * 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/6-3 1 1 G* * //RHF/6-3 1 1 G* * ,RHF/6-3 1 1 +G* * //RHF/6-3 1 1 +G* * ,MP2( Full) /6-3 1 1 +G* * //RHF/6-3 1 1 +G* *和 B3 LYP/6-3 1 1 +G* * //B3 LYP/6-3 1 1 +G* *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/6-3 1 1 +G* * //RHF/6-3 1 1 +G* *和 B3 LYP/6-3 1 1 +G* * //B3 LYP/6-3 1 1 +G* *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。The conformation, aromaticity and gas phase acidity(free energy of deprotonation, Δ G 0) 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 ZZ isomer 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 ASE and 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 Δ G 0 1, 298 K = 1 295.4 kJ/mol and Δ G 0 2, 298 K =1 691.2 kJ/mol. [WT5HZ]

关 键 词：二硫方酸 从头算 芳香性 气相酸性 

分 类 号：O623.543[理学—有机化学] O621.13[理学—化学]