全金属阳离子团簇X^+_3(X=Au,Ag,Cu)芳香性的理论研究

Theoretical study on the aromaticity of the cationic all-metal clusters X^+_3(X=Au,Ag,Cu)

运用密度泛函理论(B3LYP)、从头算方法(HF,MP2),对全金属阳离子团簇X3+(X=Au,Ag,Cu)的稳定结构、振动频率、原子化能(atomization energy,AE)、最高占据态和最低空轨道能隙(homo-lumo gap)与电子总能量(考虑了零点能ZPE)作了理论计算.全金属阳离子团簇X3+(X=Au,Ag,Cu)的稳定结构是D3h.在此基础上,研究了全金属阳离子团簇X3+(X=Au,Ag,Cu)环状平面结构D3h的两种磁性质:各向异性磁化率(χanis)和核独立位移(NICS).计算结果表明:环状平面结构的全金属阳离子团簇X3+(X=Au,Ag,Cu)具有很强的芳香性特征.对它们的分子轨道分析表明,环状平面全金属阳离子团簇X3+(X=Au,Ag,Cu)具有多重芳香性,两个σ分子轨道和一个π分子轨道对全金属阳离子团簇X3+(X=Au,Ag,Cu)的芳香性起着重要的作用.

The optimized geometries, frequencies, atomization energies, homo-lumo gaps and total energies of three all-metal clusters X＋ a （X=Au, Ag, Cu） are calculated at the B3LYP, HF and MP2 levels of theory. On the basis of structure Dab that we focus on computing two magnetic properties： magnetic susceptibility（xanis） and nucleus-inde- pendent chemical shift（NICS）. The computed results of Xanis and NICS show that the all- metal clusters X＋ （X= Au, Ag, Cu） possess strong aromaticity. The detailed molecular analysis for all-metal clusters X＋ （X=Au, Ag, Cu） further reveals that it have multiple fold aromaticity： delocalized two a Mos and one 7r Mos which play important role in ex- plaining the special stability of these all-metal clusters.