Thallophilic interactions and Tl-aryl pi -interactions are competitive with cation-cation repulsion: [LTl sub(2)L] super(2+) dications as salts of weakly co-ordinating anions

The synthesis and characterization by single-crystal X-ray diffraction of two thallium salts of the non-co-ordinating anion [B{3,5-(CF sub(3)) sub(2)C sub(6)H sub(3)} sub(4)] are reported. They possess Tl-Tl contacts supported by Tl-aryl interaction. This cation association overcomes both electrostatic repulsion and cation-anion size and charge matching considerations in the [LTl sub(2)L] super(2+) dications so formed.