Crowning of Coinage Metal Pyrazolates: Double-Decker Homo- and Heteronuclear Complexes with Synergic Emissive Properties

A new pyrazole ligand with flexible thioether chelate arms was synthesized and was used to obtain an unprecedented class of hexanuclear coinage metal complexes of general formula [MM′L]3Y3 (M, M′ = Cu, Ag, Au; Y = OTf, BF4). Three of them were characterized by X-ray crystallography, namely, homometallic [Ag2L]3(OTf)3 and [Ag2L]3(BF4)3 as well as heterometallic [CuAgL]3(OTf)3, revealing that the classical [M­(μ-pz)]3 core is crowned by a second deck of S-bound M′ ions. Depending on the solvent, these oligonuclear systems undergo rapid dynamics and show cation–anion aggregation in solution, which has been investigated by DOSY and temperature dependent NMR spectroscopy. Preliminary luminescence data for selected hexametallic [MM′L]3Y3 complexes show that the combination of ligand-directed intramolecular and supramolecular d10 metal ion interactions in the solid state gives rise to synergic emissive properties that allow for a selective addressing of different emission wavelengths.