Two novel halogeno(cyano)argentates built by silver halide clusters: molecular structures and luminescent properties

Abstract

Two novel halogeno(cyano)argentates(I), [Et₄N]₃[Ag₆(CN)_3.39Br_5.61] (1) and [Pp₄N]₃[Ag₈(CN)₄I₇] (2) (Et₄N = tetra-ethylammonium, Pp₄N = tetra-n-propylammonium), were obtained by the solvothermal reaction of silver(I) cyanide with tetraalkylammonium salts in anhydrous THF. Complex 1 presents a 2-D grid-like sheet built by [Ag₆Br₅]⁺ clusters bridged by cyanide groups. Complex 2 is the first example of 3-D halogeno(cyano)argentates(I), and displays a porous framework with fluorite (flu) topology based on [Ag₄I₄] and an unprecedented [Ag₈I₆]²⁺ cluster, respectively, as 4-connected and 8-connected nodes. The optical and luminescent properties of the two complexes have been investigated. On the basis of Time-dependent Density Functional Theory calculations, the emission spectrum of 1 can be assigned as metal-centred (MC) transitions, while the luminescence behavior for 2 is assumed to arise from metal-to-ligand charge-transfer (MLCT) transitions.