Photophysical Investigation of Silver/Gold Dicyanometallates and Tetramethylammonium Networks: An Experimental and Theoretical Investigation

We report on the structural and luminescence properties of a series of d10 dicyanometallate compounds of formula K3(Me4N)2[M(CN)2]5 (M = Au and Ag). These double salts form isostructural 3D networks in which metallophilic bonding is observed between [M(CN)2]– subunits. Despite their similar structural features, stark differences in luminescence behavior between these crystals are observed. At room temperature Au‐containing crystals are bright emitters at 405 nm while the Ag analog is a weak emitter at 470 nm. At low temperatures the emission of both complexes becomes intense under UV light at a wavelength of 416 nm. Using lifetime measurements, X‐ray crystallography, and Density Functional Theory (DFT) calculations we have been able to assign these emission bands as a transition from a metal‐metal to ligand charge transfer. Networks of [Au(CN)2]– and [Ag(CN)2]– using the cation tetramethylammonium are structurally and photophysical characterized. Temperature‐ and time‐dependent luminescence, supported with DFT calculations, indicate a temperature dependent dual fluorescence/phosphorescence emission pathway in the case of Au.