摘要
在RHF/6-311G水平优化得到3,4-二硒方酸(3,4-二氢硒基-3-环丁烯-1,2-二酮)3 种平面构象异构体的平衡几何构型。进一步用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/6-311+ G//RHF/6-311+ G、MP2(full)/6-311+ G//RHF/6-311+ G 和B3LYP/6-311+ G//B3LYP/6-311+ G水平计算其气相酸性(ΔG°)和同键反应芳香性稳定化能(HASE)。用基团加和法(group increm ent ap-proach ) 在 RHF/6-311 + G//RHF/6-311 + G 和 B3LYP/6-311 + G//B3LYP/6-311+ G水平计算其磁化率增量(Λ)。计算结果指出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。
The conformation, aromaticity and gas phase acidity(free energy of deprotonation, ΔG ° ) of 3,4 diselenosquaric acid (3,4 diselenyl 3 cyclubutene 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 1,2 diselenosquaric acid presents a planar conformation. The ZZ isomer was found to be the most stable of the three planar conformers. The homodesmotic reaction aromatic stabilization energy (HASE) and magnetic susceptibility exaltation( Λ ) were also computed by using the SCF CSGT(Continues Set of Gauge Transformations) (IGAIM, a slight variation on CSGT) and B3LYP CSGT(IGIAM) methods at the 6 311+G(d,p) level. The calculated HASE and Λ were much negative magnitudes, indicating that 3,4 diselenosqaric acid is aromatic. Thus the title compound fulfilled the geometrical, energetic and magnetic criteria of aromaticity. The most reliable theoretical gas phase acidity are ΔG ° 1(298k) =1280.7kJ/mol and ΔG ° 2(298k) =1665.7 kJ/mol.\;
基金
结构化学国家重点实验室基金
福建省自然科学基金
福建省高等学校科研基金
关键词
二硒方酸
从头算
芳香性
气相酸性
酸性
diselenosquaric acid, \$ab initio,\$ density functional theory(DFT) aromaticity, gas phase acidity