Ag6Cl4: the first silver chloride with rare Ag6 clusters from an ab initio study.

The first diamagnetic semiconducting silver subhalide, Ag6Cl4, featuring rare subvalent Ag6 clusters with 2e--6c bonds, 1D argentophilic d10-d10 intercluster interactions and 3D ionic connectivity ensured by Cl atoms has been predicted employing Density Functional Theory. Ag6Cl4 carries all unique features of Ag+ so far observed only in selected metal-rich oxides and as such represents an important addition to the discussion of the special bonding properties of silver with a filled d10-shell. Having appreciable formation enthalpy and dynamical stability, Ag6Cl4 should be in principle possible to synthesize as a metastable phase relative to AgCl.