Syntheses and conversions of dinuclear cadmium(ii) compounds containing N2O/N2O2 donor tridentate/tetradentate asymmetrical Schiff base ligands

Abstract

Through different synthetic strategies, four dinuclear cadmium(II) complexes containing N₂O/N₂O₂ donor tridentate/tetradentate asymmetrical Schiff base ligands have been synthesized and characterized. The two complexes [Cd(L¹)(μ²-Cl)(CH₃OH)]₂ (1) and [Cd(L²)Cl]₂·CH₃OH (2) are constructed, respectively, from self-assembly of a Cd²⁺ ion with two asymmetrical Schiff base ligands, namely 2-((2-(dimethylamino)ethylimino)methyl)phenol (HL¹) and 2-((2-(dimethylamino)ethylimino)methyl)-6-methoxyphenol (HL²). However, via single-crystal to single-crystal structural transformations driven by temperature, the other two corresponding compounds [Cd(L¹)Cl]₂ (1a) (1 → 1a) and [Cd(L²)Cl]₂ (2a) (2 → 2a), with N₂O₂Cl and N₂O₃Cl donors, respectively, can be obtained. Obviously, the synthetic strategies presented in the text provide very effective methods for constructing the dinuclear Cd^II compounds with N₂O/N₂O₂ donor tridentate/tetradentate asymmetrical Schiff base ligands. Meanwhile, the strong fluorescence emission of 1 and 2 makes them potentially useful photoactive materials.