Hydrogen Bonding Influenced Coordination Mode of Azide Ligand in Schiff base Copper(II) Complexes: Synthesis, Crystal Structures, and Antibacterial Activity

Abstract

Two copper(II) complexes, [CuL¹N₃] (I) and [CuL²(μ_1, 1-N₃)] (II), where L¹ = 2-[(2-diethylaminoethylimino)methyl]-4,6-difluorophenolate, L² = 2,4-difluoro-6-[(2-isopropylaminoethylimino)-methyl]phenolate, have been prepared and structurally characterized by elemental analyses, IR and UV-Vis spectra, as well as single crystal X-ray determination (CIF files CCDC nos. 1848289 (I) and 1848290 (II)). In complex I, the Cu atom is in square planar coordination, with the azide ligand in terminal coordination mode. In complex II, the Cu atom is in square pyramidal coordination, with the azide ligand in end-on bridging mode. The crystals are stabilized by hydrogen bonds, which influence the coordination mode of the azide ligand. The complexes have strong antibacterial activity against B. subtilis and S. aureus.