Caramori Giovanni F, Piccoli Rafael M, Segala Maximiliano, Muñoz-Castro Alvaro, Guajardo-Maturana Raul, Andrada Diego M, Frenking Gernot
Departamento de Química, Universidade Federal de Santa Catarina, CP 476, Florianópolis, SC 88040-900, Brazil.
Dalton Trans. 2015 Jan 7;44(1):377-85. doi: 10.1039/c4dt02514h.
The metal-ligand, M-L, bonding situation in cyclic trinuclear complexes, CTCs, of copper(I), silver(I), and gold(I) was investigated in terms of the energy decomposition analysis (EDA-NOCV) and natural bond orbitals (NBOs). The anisotropy of the induced current density (ACID) and magnetic response were employed to evaluate the effect of electronic conjugation and metal-metal interactions in CTCs. The EDA-NOCV results show that the M-L bonding is stronger in gold(I) than in copper(I) or silver(I) complexes. Au(+)-L bonds present an elevated covalent character when compared with Cu(+)-L and Ag(+)-L bonds. The NBO analysis confirms the elevated covalent character observed for Au(+)-L bonds, indicating that the ligand-metal donation, L → M, and the metal-ligand back-donation, M → L, are more stabilizing in gold(I) than in copper(I) or silver(I) complexes. Both ACID and the magnetic response calculations reveal that there are cyclic conjugations in the ligands and a strong diatropic ring current indicating the presence of aromaticity. However, there is no through-bond M-L conjugation between the ligands and the metallic centers, as indicated by the absence of a continuous anisotropy boundary surface involving M-L bonds.
通过能量分解分析（EDA-NOCV）和自然键轨道（NBO）对铜（I）、银（I）和金（I）的环状三核配合物（CTCs）中的金属-配体（M-L）键合情况进行了研究。利用感应电流密度各向异性（ACID）和磁响应来评估CTCs中电子共轭和金属-金属相互作用的影响。EDA-NOCV结果表明，金（I）配合物中的M-L键比铜（I）或银（I）配合物中的更强。与Cu（+）-L和Ag（+）-L键相比，Au（+）-L键具有更高的共价性。NBO分析证实了Au（+）-L键具有更高的共价性，表明配体-金属给予作用（L→M）和金属-配体反馈作用（M→L）在金（I）配合物中比在铜（I）或银（I）配合物中更稳定。ACID和磁响应计算均表明，配体中存在环状共轭，且有强烈的抗磁环电流，表明存在芳香性。然而，由于不存在涉及M-L键的连续各向异性边界表面，表明配体与金属中心之间不存在通过键的M-L共轭。
