“…First of all, Tl-Tl contacts shorter than 3.92Å (i.e. 2 × r vdW (Tl) [28]) are found in many classes of compounds, as simple inorganic salts, e.g., TlF (the shortest Tl-Tl distance: 2.59Å) [29] and TlNO 3 (Tl-Tl: 3.05Å) [30], some organometallics, e.g., Tl 4 (OR) 4 , R = Me, Et, n-Pr (Tl-Tl: 3.83Å) [31], some intermetallics, e.g., Li 5 Tl 2 (Tl-Tl: 3.01Å) [32] and KTl (Tl-Tl: 3.06-3.08Å) [33], as well as in many coordination compounds, e.g., [As(C 6 H 5 ) 4 ][Tl 2 {μ-Mn(CO) 4 (μ-H)Mn 3 (CO 12 } 2 ] (Tl-Tl 3.632Å) [34] and a series of pyrazolate complexes (Tl-Tl: 3.53Å) [35].…”