Luminescence properties of some monomeric and dimeric cycloplatinated(II) complexes containing biphosphine ligands

The starting complexes [PtCl(2C boolean AND N)(dmso)], in which C boolean AND N is either ppy = 2-phenylpyridinate, 1a, or bhq = 7,8-benzo[h]quinolinate, 2a, were prepared by a known method using the reaction of [PtCl2(dmso)(2)] with ppyH or bhqH, respectively, in toluene under reflux conditions. The reaction of [PtCl(C boolean AND N)(dmso)], 1a or 2a, with 1 equiv. of a number of biphosphine ligands, P boolean AND P, gave the cationic monomeric complexes [Pt(ppy)(P boolean AND P)]Cl, for which P boolean AND P is either 1,2-bis(diphenylphosphino) ethane (dppe), 3a, 1,3-bis(diphenylphosphino) propane (dppp), 3c, or bis(diphenylphosphino) methane (dppm), 3d; the bhq analogous complex [Pt(bhq)(dppe)] Cl, 4a, was prepared similarly. However, the complex [Pt(ppy)(dfppe)]Cl, 3b, in which dfppe is 1,2-bis(dipentafluorophenylphosphino) ethane, was prepared by the reaction of 1a with excess amount of dfppe. When each of the starting complexes [PtCl(C boolean AND N)(dmso)], 1a or 2a, were reacted with 0.5 equiv. of any of the P boolean AND P ligands, the dimeric complexes [Pt2Cl2(ppy)(2)(mu-P boolean AND P)], 5a-5d, or [Pt2Cl2(bhq)(2)(mu-P boolean AND P)], 6a-6b, were formed. The complexes were fully characterized using multinuclear (H-1 and P-31) NMR spectroscopy and elemental analysis. The structures of typical complexes 3a, 3c, 5b, and 5d were also confirmed by X-ray crystallography. The effect of ligands on the luminescent properties of the complexes was investigated and DFT calculations were performed to confirm the assignments.