Synthesis, Crystal Structures, and Antibacterial Activity of Manganese(III) Complexes with Schiff Bases

Abstract

Two new manganese(III) complexes, [MnL¹(EtOH)(Acac)] (I) and [MnL²(DMF)(Esal)] · H₂O (II), where L¹ and L² are the dianionic form of 2-[(2-hydroxyphenylimino)methyl]-6-methoxyphenol (H₂L¹) and 4-chloro-2-[(3-ethoxy-2-hydroxybenzylidene)amino]phenol (H₂L²), respectively, Acac is acetylacetone, Esal is 3-ethoxysalicylaldehyde, were prepared and characterized by IR and UV-Vis spectra, as well as single crystal X-ray diffraction (CIF files CCDC nos. 1849854 (I) and 1849855 (II)). Complex I crystallizes as the hexagonal space group P\(\bar {3}\) with unit cell dimensions a = b = 20.4482(9), c = 8.6952(7) Å, V = 3148.6(3) ų, Z = 6, R₁ = 0.0375, wR₂ = 0.0957, GOOF = 1.050. Complex II crystallizes as the triclinic space group P¯1 with unit cell dimensions a = 8.1602(12), b = 11.5960(15), c = 15.3859(13) Å, α = 78.873(2)°, β = 83.766(2)°, γ = 84.964(2)°, V = 1416.7(3) ų, Z = 2, R₁ = 0.0733, wR₂ = 0.1795, GOOF = 1.029. X-ray analyses indicate that the complexes are manganese(III) species, with the Mn atoms in octahedral coordination. The Schiff bases and the complexes were evaluated for their antibacterial (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas fluorescence) activities.