Synthesis, structure, optical properties and theoretical studies of Pt(P-P)(CN)(2) with P-P=1,2-bis(diphenylphosphanyl)benzene and 2,2 '-bis(diphenylphosphanyl)-1-1 '-binaphthyl - Luminescence from metal-to-ligand charge transfer and intraligand stat

摘要

The complexes Pt-II(P-P)(CN)(2) with P-P = 1,2-bis(diphenylphosphanyl)benzene (dppb) and 2,2'-bis(diphenylpliosphanyl)-1,1'-binaphthyl (binap) were synthesised and characterised by elemental analysis, ESI MS and electronic spectroscopy. ;The structure of Pt(dppb)(CN)(2) was resolved by single-crystal X-ray diffraction. This compound consists of mononuclear Pin complexes with an almost planar PtP2C2 CO-ordination. While both complexes are not luminescent in solution, they show an emission in the solid state under ambient conditions. It is suggested that the luminescence of Pt(dppb)(CN)(2) originates from a (Pt-II --> dppb) metal-to-ligand charge transfer (MLCT) triplet with some dppb intraligand (IL) contribution. This assignment is confirmed by calculations which provide further insight into the excited state properties of the complex. In solution the phosphorescence is absent because the MLCT/IL state is deactivated to a nonemissive ligand field (LF) triplet, which is located at rather low energies owing to its distortion towards a tetrahedral structure. In the solid state this distortion is hindered. In the case of solid Pt(binap)(CN)(2), the phosphorescence is apparently of the IL type as the pipi* triplet of the binaphthyl chromophore occurs at low energies. Again, in solution the phosphorescence is absent owing to the interference by a distorted LF state. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004).