Effects of the Au(I)-Au(I) closed-shell attraction on the electronic and phosphorescent properties in a series of coordination compounds: A theoretical study

摘要

The Au(I)-Au(I) closed-shell or aurophilic attraction has been the subject of interest in the experimental and theoretical chemistry fields, due to the intriguing properties associated to it. The presence of phosphorescence in "aurophilic" compounds has been addressed to a wide range of applications, but it has not yet been fully understood. A theoretical study on the electronic and phosphorescent properties of the following series of dinuclear gold complexes has been performed: [Au_2(dmpm) (i-mnt)] (1), [Au_2(μ-Me-TU) (μ-dppm)] (2), and [Au_2(μ-G)(μ- dmpe)] (3). Full geometry optimizations at the second-order M?ller- Plesset perturbation theory (MP2) were carried out for each of the species. These calculations made evident that, at the ground-state geometry, the Au(I) cations allocated at the center of the ring show a short Au-Au distance below the sum of the van der Waals radii, at the range of the aurophilic attraction. An intermolecular Au(I)-Au(I) closed-shell attraction for a pair of the systems under study is found. This attraction is comparable to that of the hydrogen bonds. The phosphorescent properties experimentally observed for this series were also characterized through ab initio techniques. The obtained results allow to fit reasonably the excitation energies with the experimental data and to identify a correlation between the strength of the Au(I)-Au(I) interaction and the phosphorescent behavior.