Counter-anion effects on the supramolecular structures of tetranuclear PtII2AgI2 complexes with 1,3-dithioglycerol and 2,2'-bipyridine.

Precisely controlling the supramolecular structures of photoluminescent metal complexes is important for tuning their solid-state functionality through intermolecular interactions. In this study, we report a platinum(II) complex bearing an aliphatic dithiolate ligand, [Pt(bpy)(Hdtg)] (H3dtg = 1,3-dithioglycerol, bpy = 2,2'-bipyridine), to construct heterometallic complexes. The reaction of [Pt(bpy)(Hdtg)] with various silver(I) salts afforded tetranuclear PtII2AgI2 complexes [Ag2{Pt(bpy)(Hdtg)}2]X2 (X = ClO4, BF4, OTf). Single-crystal X-ray diffraction analysis revealed that the cationic PtII2AgI2 core was essentially identical among the complexes, whereas their supramolecular structures varied depending on the counter-anion. These differences led to distinct metallophilic contacts; in particular, the OTf- salt showed AgI⋯AgI⋯PtII interactions in the solid state. Absorption and emission measurements and density functional theory calculations indicated that the supramolecular interactions influenced the electronic structures and emission properties of the complexes. This study demonstrated that PtII-aliphatic dithiolato complexes can serve as metalloligands for constructing heterometallic assemblies whose solid-state structures are sensitive to counter-anion effects.