Neutral and Cationic Palladium(II) and Platinum(II) Complexes of 2,2′-Dipyridylamine with Saccharinate: Syntheses, Spectroscopic, Structural, Fluorescent and Thermal Studies

Abstract

Four palladium(II) and platinum(II) complexes of 2,2′-dipyridylamine (dpya) with saccharinate (sac), cis-[Pd(dpya)(sac)<inf>2</inf>]·H <inf>2</inf>O (1), cis-[Pt(dpya)(sac)<inf>2</inf>]·H<inf>2</inf>O (2), [Pd(dpya)<inf>2</inf>](sac)<inf>2</inf>·2H<inf>2</inf>O (3) and [Pt(dpya)<inf>2</inf>](sac)<inf>2</inf>·2H<inf>2</inf>O (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. © 2010 Elsevier B.V. All rights reserved.