Metal-metal stacking patterns between and with [Pt(tpy)X] cations

A comparative study of metallophilic interactions of Pt(tpy)X]⁺ cations (tpy = 2,2′:6′,2″-terpyridine) in the presence of two different types of anions, (i) ]⁻ anions that form double salts and (ii) simple p-block anions, is reported. Single-crystal X-ray diffraction data, solution-state ¹⁹⁵Pt NMR spectra, and variable temperature solid-state luminescence spectra are reported. Three Pt(tpy)Cl]Y derivatives (Y = SbF₆, 1, SbF₆·CH₃CN, 4, PF₆, 2) and the Pt(tpy)Br]PF₆ analog, 3, as well as two new double salts Pt(tpy)CN]Au(CN)₂], 5, and Pt(tpy)CN]₂Au(C₆F₅)₂](PF₆), 6, have been synthesized and characterized. Structural analysis shows consistent patterns in Pt···Pt interactions that vary slightly depending on the coordinating halogen or pseudo-halogen X, counter anion Y, and lattice solvent. Metallophilic interactions are seen between Pt(tpy)X]⁺ cations with all types of X ligands, but only with π-accepting X′ ligands from ]⁻ anions are Pt?Au metallophilic interactions seen to be favored over Pt?Pt interactions. The Au(CN)₂]⁻ anion consistently forms Pt···Au metallophilic contacts, unlike Au(C₆F₅)₂]⁻. The ¹⁹⁵Pt NMR chemical shifts are ∼−2750 ppm for π-donor ligands and near −3120 ppm for π-acceptor ligands in Pt(tpy)X]PF₆ compounds. Luminescence data show an unusual blue shift in Pt(tpy)CCPh]Au(C₆F₅)₂] versus Pt(tpy)CCPh]PF₆ ascribed to an intermolecular charge transfer.