On the Halide Aggregation into [Au4(PPh3)4]4+ Cluster Core. Insights from Structural, Optical and Interaction Energy Analysis in [(Ph3PAu)4X2]2+ and [(Ph3PAu)4X]3+ species (X=Cl-, Br-, I-)

The aggregation of halide atoms into gold clusters offers an interesting scenario for the development of novel metal-based cavities for anion recognition and sensing applications. Thus, further understanding of the...The aggregation of halide atoms into gold clusters offers an interesting scenario for the development of novel metal-based cavities for anion recognition and sensing applications. Thus, further understanding of the different contributing terms leading to an efficient cluster-halide aggregation is relevant to guide synthetic design. In this report, we evaluate the formation of [(Ph3PAu)4X2]2+ and [(Ph3PAu)4X]3+ species (X=Cl-, Br-, I-) in terms of different energy contributions underlying the stabilization of the cluster-halide interaction, and the expected UV-vis absorption profiles as a result of the variation in frontier orbitals arrangements. Our results denote that a non-planar Au4 core shape enables an enhanced halide aggregation, which is similar for Cl-, Br-, and I-, in comparison to the hypothetical planar Au4 counterparts. The electrostatic nature of the interaction involves a decreasing ion-dipole term along with the series, as for iodine species, higher-order electrostatic contributions become more relevant. Hence, the obtained results serve to gain further understanding of the different stabilizing and destabilizing contributions for suitable cluster-based cavities for the incorporation of different monoatomic anions.