Induced phosphorescence from Pt → Ag and Ag(i)...Ag(i) metallophilic interactions in benzenedithiolatodiimine-Pt2/Ag2 clusters: a combined experimental and theoretical investigation

We report the synthesis and luminescence properties of a novel platinum(ii)-silver(i) cluster exhibiting supramolecular donor-acceptor dative Pt → Ag bonds as well as d(10)...d(10) argentophilic interactions. This compound was obtained by a self-assembly process upon mixing silver triflate with the [Pt(bdt)(bpy)] (1) building block. The new compound was characterized by infrared, NMR ((1)H, (13)C) and UV-vis spectroscopy. In addition, the molecular structure was unequivocally ascertained by a single-crystal X-ray diffraction study and shows that the assembly is identified as [(Pt2Ag2(o-bdt)2(bpy)2](CF3SO3)2 (2). Remarkably, the structure shows that complex 2 exists as two isomers I and II displaying different types of argentophilic interactions Ag...Ag as well as Pt → Ag dative bonds. These interactions are highly important and turn on phosphorescent emissions at low temperature depending on the nature of the isomer. The photophysical properties of both isomers were investigated and rationalized through TD-DFT calculations. This work paves the way to the synthesis of novel supramolecular assemblies displaying peculiar properties imparted from metallophilic as well as donor-acceptor metal-metal interactions.