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

Abstract

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) [ AuX 2 ′ ] − 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 = SbF 6, 1, SbF 6·CH 3CN, 4, PF 6, 2) and the [Pt(tpy)Br]PF 6 analog, 3, as well as two new double salts [Pt(tpy)CN][Au(CN) 2], 5, and [Pt(tpy)CN] 2[Au(C 6F 5) 2](PF 6), 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 [ AuX 2 ′ ] − 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(C 6F 5) 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]PF 6 compounds. Luminescence data show an unusual blue shift in [Pt(tpy)CCPh][Au(C 6F 5) 2] versus [Pt(tpy)CCPh]PF 6 ascribed to an intermolecular charge transfer.