Anionic cyclometalated Pt(ii) and Pt(iv) complexes respectively bearing one or two 1,2-benzenedithiolate ligands

Abstract

Novel anionic cyclometalated Pt(II) square-planar complexes NBu₄[(C^N)Pt^II(S^S)], containing 2-phenylpyridine H(PhPy), 2-(2,4-difluorophenyl)-pyridine H(F₂PhPy) and benzo[h]quinoline H(Bzq), respectively, as a cyclometalated ligand and the dianionic 1,2-benzenedithiolate (Thio)²⁻ fragment as an (S^S) ligand, were synthesised. By the simple addition of an equivalent of (Thio)²⁻ to the NBu₄[(C^N)Pt^II(Thio)] complexes, octahedral anionic NBu₄[(C^N)Pt^IV(Thio)₂] analogues were obtained, representing, to the best of our knowledge, the first examples of Pt(IV) anionic cyclometalated complexes. The molecular structures of the obtained complexes in the case of the NBu₄[(Bzq)Pt^II(Thio)] and the NBu₄[(Bzq)Pt^IV(Thio)₂] complexes were confirmed by single crystal X-ray diffraction analysis. Furthermore, the electrochemical and photophysical properties of the two series of Pt(II) and Pt(IV) newly synthesised complexes were studied and DFT and TD-DFT calculations were performed in order to comprehensively investigate the displayed behaviour. All Pt(II) and Pt(IV) complexes show intense luminescence in the solid state, with remarkable enhancement of the emission quantum yields, proving to be excellent examples of aggregation-induced emission systems.