Non-covalent interactions between cations in the crystal structure of [Pt{4′-(p-tolyl)trpy}Cl]SbF6, where trpy is 2,2′:6′,2″-terpyridine, underpin the salt’s complex solid-state luminescence spectrum

Abstract

The synthesis and characterization of [Pt{4′-(p-tolyl)trpy}Cl]SbF6 is described where trpy is 2,2′:6′,2″-terpyridine. A single crystal X-ray structure determination at 100K shows that the cations are stacked in columns that comprise cations arranged in a staircase motif. Successive cations within a column are linked by π(trpy)–π(phenyl) stabilizing interactions; and each cation in one column is linked to a cation in an adjacent column by a weakly stabilizing Pt···Pt interaction. The Pt···Pt distance is 3.434(1)Å. The metrics governing non-covalent interactions between [Pt{4′-(aryl)trpy}Cl]+ cations have been analyzed for the present structure and related structures in the CSD (Cambridge Structural Database). Cation dimers cluster into three distinct groups based on their lateral shifts and, to a lesser extent, the angular parameters governing their relative displacements; the dominant grouping exhibits Pt···Pt and π(trpy)–π(trpy) stabilizing interactions. An emission spectrum recorded at 77K on a solid sample of the compound is best interpreted as arising from the decay of three photoexcited states: a 3MLCT (MLCT=metal-to-ligand charge transfer) state; a 3MMLCT (MMLCT=metal–metal-to-ligand charge transfer) state, and an excimeric 3π–π∗ state.