NO_2大π键量子化学研究  

Quantum chemical study on delocalized π-bond of NO_2

作　　者：张金生[1] 汪荣凯[1] 王光彦[1] 

机构地区：[1]贵州师范大学化学与材料科学学院,贵州贵阳550001

出　　处：《贵州师范大学学报（自然科学版）》2011年第4期76-79,共4页Journal of Guizhou Normal University：Natural Sciences

基　　金：贵州省科学技术基金(黔科合J字[2009]2241号);贵州师范大学博士启动基金

摘　　要：用量子化学从头算MP2、QCISD、CCSD方法结合6-311++G(3df,3pd)基组的计算水平以及休克尔分子轨道(HMO)理论对基态NO2大π键进行了研究。结果显示,基态NO2中氮原子接近sp2杂化。未参与成键的杂化轨道电子占据数约为0.99。大π键中成键电子和反键电子总数均约为3.62;,而自然键轨道(NBO)理论计算出NO2分子中存在3中心4电子大π键,参与离域的电子总数约为3.98;HMO法计算表明,具有Π43键的NO2分子比存在Π33键的NO2分子能量低187.855 kJ/mol。故基态NO2分子中存在Π34键的说法更合理。By means of quantum chemical ab initio MP2, QCISD, CCSD theory and Huckel molecular orbital （HMO） method, the delocalized π-bond of NO2 was studied. The calculation suggesed that the nitragon atom in ground-NO2 was sp2 hybridization. The none-bonding hybridized atomic orbital was occupyzed by 0. 99 electrons. Moreover, 3.62 electrons occupied the π- and π -bond. The natural bond orbital analysis indicated that 3. 98 electrons occupied a three-center four-electron w-orbital. The HMO study showed that the energy of NO2 system with П3^4 bond was lower than that with П3^4 bond by 187. 855kJ/mol. Thus at the ground state, the description of NO2 possessing a П3^4 bond was more reasonable.

关 键 词：大π键 从头算 休克尔分子轨道法 三中心四电子键 角扩张 

分 类 号：O6-041[理学—化学]