Biscyclometalated platinum complexes with thiophene ligands

The reaction of [Pt-2(CH3)(4)(mu-S(CH3)(2))(2)] with four equivalents of ligand C4H3SCH=NCH2C6H5 gives the platinum (II) complex [Pt{(C4H2S)CH=NCH2C6H5}(2)] with two cyclometalated C N ligands. [Pt{(C4H2S)CH=NCH2C6H5}(2)] can also be prepared by refluxing the monometalated species [Pt(C4H2SCH=NCH2C6H5)CH3(S(CH3)(2))], alone in toluene or with the additionofone equivalent of ligand C4H3SCH=NCH2C6H5. Similar reactions were observed for [Pt-2(CH3)(4)(mu-S(CH3)(2))(2)] with the ligands (S)-C4H3SCH=NCHCH3C6H5 and C4H3SCH=NC6H5, and the corresponding monocyclometalated species. A mechanism of formation is proposed with the support of DFT calculations. The complexes show emission, in solution, at room temperature, with emission bands red-shifted similar to 200 nm, excited state lifetimes of the order of 1 mu s, and modest quantum yields up to 0.012. DFT calculations were used to assist in the assignment of the electronic spectroscopy. (C) 2012 Elsevier B.V. All rights reserved.