Chen Jing, Luo Zhixun, Yao Jiannian
State Key Laboratory for Structural Chemistry of Unstable and Stable Species, and Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Phys Chem Chem Phys. 2017 Aug 16;19(32):21777-21782. doi: 10.1039/c7cp02538f.
Utilizing a strong electron acceptor molecule tetracyanoquinodimethane (TCNQ) as probe, we demonstrate how the electronic features and geometric sites determine charge-transfer interactions of noble metal clusters with organic molecules. First-principle calculations by searching local minimum energies suggest that the TCNQ complexes with Ag, AuAg, AuAg and Au all favor edge-site adsorption, and their structures are highly comparable and possess metal-N-metal bonds. Further analysis on frontier molecular orbitals (FMOs) and natural population analysis (NPA) reveals that it's easier for Ag/AuAg clusters to transfer electrons to TCNQ as compared with Au/AgAu. Spin density isosurfaces indicate that the charge transfer from these 13-atom clusters to TCNQ leads to electronic shell closure of the metal clusters. The difference in the electronegativities of Ag and Au, as well as the significant relativistic effect of gold, results in varying donor-accepter interactions sensitive to the coordination number of the doping atom for both AuAg and AuAg clusters.
利用强电子受体分子四氰基对苯二醌二甲烷（TCNQ）作为探针，我们展示了电子特征和几何位点如何决定贵金属簇与有机分子之间的电荷转移相互作用。通过搜索局部最小能量进行的第一性原理计算表明，TCNQ与Ag、AuAg、AuAg和Au形成的配合物均倾向于边缘位点吸附，且它们的结构高度可比并具有金属 - N - 金属键。对前线分子轨道（FMO）和自然布居分析（NPA）的进一步分析表明，与Au/AgAu相比，Ag/AuAg簇更容易将电子转移到TCNQ。自旋密度等值面表明，从这些13原子簇到TCNQ的电荷转移导致金属簇的电子壳层闭合。Ag和Au电负性的差异以及金的显著相对论效应，导致对于AuAg和AuAg簇而言，供体 - 受体相互作用对掺杂原子配位数敏感程度不同。
