Neutral and cationic palladium(II) and platinum(II) complexes of 2,2′-dipyridylamine with saccharinate: Syntheses, spectroscopic, structural, fluorescent and thermal studies

Four palladium(II) and platinum(II) complexes of 2,2′-dipyridylamine (dpya) with saccharinate (sac), cis-[Pd(dpya)(sac)2]·H2O (1), cis-[Pt(dpya)(sac)2]·H2O (2), [Pd(dpya)2](sac)2·2H2O (3) and [Pt(dpya)2](sac)2·2H2O (4), have been synthesized and characterized by elemental analysis, IR, NMR, TG-DTA and X-ray diffraction. In 1 and 2, the metal ions are coordinated by two N-bonded sac ligands, and two nitrogen atoms of dpya, resulting in a neutral square-planar coordination sphere, while in 3 and 4, the metal ions are coordinated by two dpya ligands to generate square-planar cationic species, which are stabilized by two sac counter-ions. The mononuclear species of 1 and 2 interact each other through weak intermolecular N–H⋯O, C–H⋯O and π⋯π interactions to form a three-dimensional network, while the ions of 3 and 4 are connected by N–H⋯N and OW–H⋯O hydrogen bonds into one-dimensional chains. On heating at 250 °C, the solid cationic complexes of 3 and 4 convert to corresponding anhydrous neutral complexes of 1 and 2 after elimination of a dpya ligand. In addition, all complexes 1–4 are luminescent at room temperature and their emissions seem to be attributed to the MLCT fluorescence.

Neutral and cationic palladium(II) and platinum(II) complexes of 2,2′-dipyridylamine (dpya) with saccharinate (sac) have been synthesized and structurally characterized. All complexes contain bidentate chelating dpya ligands. In the neutral complex cis-[M(dpya)(sac)2]·H2O (M = PdII or PtII), two sac anions coordinate the metal(II) ions via the imino N atom, while in the cationic complex [M(dpya)2](sac)2·2H2O, they remain outside the coordination sphere as counter-ions. The solid cationic complexes convert to the corresponding solid neutral complexes due to the thermal elimination of a dpya molecule.Figure optionsDownload as PowerPoint slide