Influence of the Crystallization Solvent on the Molecular Structures of Copper(II) Saccharinato Complexes with Pyridazine: Synthesis, X-Ray Crystallography, Spectroscopy, Photoluminescence, and Thermal Properties

Abstract

X-Ray structural analysis has shown that the products of the reaction of [Cu(sac)<inf>2</inf>(H<inf>2</inf>O)<inf>4</inf>]·2H<inf>2</inf>O (sac ≤ saccharinate) with pyridazine (pydz) are markedly dependent on the solvent used in the crystallization. The mononuclear complex [Cu(sac)<inf>2</inf>(H <inf>2</inf>O)(pydz)<inf>2</inf>] is obtained by slow evaporation of a 1:2 H<inf>2</inf>O/methanol solution at room temperature, whereas liquid-phase diffusion of diethyl ether into the same reaction solution produces the polymeric complex [Cu(μ-OH)(μ-sac)(μ-pydz)]<inf>n</inf>. The individual molecules of [Cu(sac)<inf>2</inf>(H<inf>2</inf>O)(pydz)<inf>2</inf>] are doubly bridged into dimers by OH...O hydrogen bonds. All ligands in [Cu(sac) <inf>2</inf>(H<inf>2</inf>O)(pydz)<inf>2</inf>] are monodentate, whereas copper(ii) ions in [Cu(μ-OH)(μ-sac)(μ-pydz)]<inf>n</inf> are triply bridged by all ligands, leading to a one-dimensional chain structure, which is further assembled to form a three-dimensional framework by non-covalent and CH stacking interactions. Complex [Cu(sac)<inf>2</inf>(H<inf>2</inf>O)(pydz) <inf>2</inf>] is paramagnetic, whereas complex [Cu(μ-OH)(μ-sac)(μ-pydz) ]<inf>n</inf> exhibits a significantly low μ<inf>effective</inf> value due to very strong exchange coupling between the copper atoms with a relatively short CuCu distance of 3.360(3) Aγ. In addition, the full spectroscopic, luminescence, and thermal properties of the complexes are reported. © CSIRO 2008.