Attachment of Luminescent Neutral “Pt(pq)(C≡CtBu)” Units to Di and Tri N-Donor Connecting Ligands: Solution Behavior and Photophysical Properties

摘要

Binuclear derivatives [{Pt(pq)(C≡CtBu)}₂(μ-L)] (1a–5a), containing a series of dinitrogen linker ligands and the trinuclear [{Pt(pq)(C≡CtBu)}₃(μ-L)] (6a) [L = μ-1,3,5-tris(pyridine-4-ylethynyl)benzene], formed by bridge-splitting reactions with [Pt(pq)(μ-κCα:η2-C≡CtBu)]₂ (Pt-1), are reported. The complexes are characterized by a combination of 1H NMR spectroscopy, mass spectrometry and X-ray crystallography (2a and 4a). 1H NMR proves the existence of a dynamic equilibrium in solution between the diplatinum complexes (species a), the corresponding mononuclear complex with terminal N-donor ligands (species b), the starting material (Pt-1) and the free ligand (L). The effects of concentration, temperature and solvent properties on the equilibrium have been studied. The optical properties of these systems have been investigated by UV-visible absorption and emission spectroscopies in solid state and in solution, and the nature of the transitions and the excited state analyzed by theoretical calculations on 2a.