Structural Isomerism of Luminescent Dinuclear Pt(II)-Thiolate Diimines

An efficient method has been developed to isolate a series of anti and syn isomers of dinuclear Pt(II)-thiolate diimines, anti-[Pt(d-t-bpy)(NS2)]2(ClO4)2 (1a), syn-[Pt(d-t-bpy)(NS2)]2(ClO4)2 (1b), anti-[Pt(d-t-bpy)(N2S)]2(PF6)2 (2a), syn-[Pt(d-t-bpy)(N2S)]2(ClO4)2 (2b), and syn-[Pt(d-t-bpy)(NOS)]2(ClO4)2 (3) (d-t-bpy = 4,4′-di-tert-butyl-2,2′-bipyridine, HNS2 = 2-mercaptobenzothiazol, HN2S = 2-mercaptobenzimidazol, HNOS = 2-mercaptobenzoxazol). In fact, it provides a rational strategy to isolate a series of anti and syn isomers of dinuclear Pt(II) thiolates, where the syn isomers all show intermolecular Pt(II)···Pt(II) contacts of 3.510(4)−3.859(4) Å. To examine the correlation between the luminescence and intermolecular Pt(II)···Pt(II) contacts, solid-state luminescence measurements of the dinuclear complexes at room temperature and at 77 K have been carried out. Indeed, there is no obvious correlation between their emission energies and intermolecular Pt(II)···Pt(II) interactions, although our theoretical calculations suggest that these interactions are involved in their excited states. However, the dinuclear complexes with larger red-shifts of 1260 (1b) and 840 cm−1 (2b) are in parallel with their increased intermolecular π···π interactions. In addition, the glass luminescence at 77 K and their concentration-dependence measurements conducted for 1a and 1b further support that intermolecular π···π interactions instead of Pt(II)···Pt(II) ones are most likely correlated with the solid-state luminescence.