对全金属La2-4团簇芳香性的从头算理论研究简

我们将芳香性扩展到全金属阴离子团簇La2-4.运用从头算方法(B3LYP/LANL2DZ,B3PW91/LANL2DZ and MP2/LANL2DZ)进行了结构优化.计算结果显示,阴离子团簇有两个同分异构体,一个是C2v结构,另一个是正方形D4h结构.进一步对能量的分析得出,D4h结构比C2v结构更稳定.对最稳定的D4h结构计算了核独立位移(NICS),结果显示正方形的La2-4环呈现强芳香性.详细的分子轨道(Mos)分析揭示正方形的La2-4环拥有四个独立的离域化成键系统,每一个系统拥有两个电子,分别满足4n+2芳香性电子计算规则,因此呈现四重芳香性.

Ab initio study on the aromaticity of all-metallic anion La42-

We extended the aromaticity concept to all-metallic anion La42- and then performed Ab intio calculations (B3LYP/LANL2DZ, B3PW91/LANL2DZ and MP2/LANL2DZ) on the selected structures. The computed results indicate that anion La42- has two stable isomers: one is the bidentate C2v structure and another is the square planar D4h structure. The further analysis on energies shows that the square planar D4h structure is more stable than the bidentate C2v structure. The computed nucleus-independent chemical shifts (NICS) on the most stable D4h structure show that the square planar La42- ring exhibits higher degree of aromaticity. The detailed Mos analysis further reveals that the square planar La42- ring possesses four independent delocalized bonding systems, each has two electrons satisfying the 4n + 2 electron counting rule of aromaticity, suggesting that these species have four-fold aromaticity.