Thallophilic Tl(i)-Tl(i) contacts mediated by Tl-aryl interactions. A computational study.

A computational study is presented of a complex of thallium with a neutral β-triketimine ligand which was found to form dimers with close Tl-Tl interactions. Single point energies, using the crystallographic structures, suggest that the system is bound only when BArF counter ions are included in the calculations. Energy decomposition analysis of the system was carried out in order to investigate the nature of the bonding. Across the methods, calculations show the electrostatic interaction to be repulsive for the dimer with no counter ions, but attractive when BArF counter ions are included. This suggests the metallophilic interaction is counter ion-mediated, requiring the anions to provide favourable electrostatics, even in the case of spatially diffuse and distant counter ions such as the 3,5-bistrifluoromethylphenyl borate ions used here.