In the framework of DFT (ABINIT package), we have performed atomic relaxations on the (Cu,Ag,Au)₂X₃⁻, X = F, Cl, Br, I, At anion series. Opposite to linear (MX₂)⁻ anions, all (M₂X₃)⁻ systems are triangular (C_2v symmetry). According to the system, we classified these anions in three categories according to the relative strength of electronegativity, chemical hardness, metallophilicity and van der Waals interaction. We found two bond-bending isomers: (Au₂I₃)⁻ and (Au₂At₃)⁻.