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Two oxidovanadium(V) complexes, [VOLLa] (1) and [VOLLb] (2), where L is the dianionic form of the Schiff base ligand 2-(((2-hydroxyethyl)imino)methyl)-6-methylphenol (H2L), La and Lb are the deprotonated forms of 3-hydroxy-2-methyl-4H-pyran-4-one (HLa) and 2-ethyl-3-hydroxy-4H-pyran-4-one (HLb), respectively, have been prepared and characterized by elemental analyses, IR, UV−Vis, 1H NMR and single−crystal X−ray crystallographic determination. The V atoms in the complexes are in octahedral coordination, with the Schiff base ligand mer-coordinated to the metal atoms through the phenolate O, imino N and hydroxyl O atoms, and with the pyrone ligands coordinated to the metal atoms through the two O atoms. The effect of the compounds on the antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans was studied.

A new mononuclear dioxomolybdenum(VI) complex, [MoO2L1], and a new linear trinuclear nickel(II) complex, [Ni{NiL2(μ1-η1:η0-OAc)(μ2-η1:η1-OAc)}2]·H2O, where L1 is the dianionic form of N,N’-bis(5-fluorosalicylidene)-1,3-propanediamine (H2L1), L2 is the dianionic form of N,N’-bis(5-fluoro-2-hydroxybenzylidene)-2-hydroxy-1,3-propanediamine (H2L2), have been synthesized and characterized by elemental analysis, FT-IR spectroscopy, and single-crystal X-ray determination. The Mo atom in the molybdenum complex is coordinated by four donor atoms of the Schiff base ligand, and two oxo groups, forming an octahedral coordination. In the nickel complex, there are three bridges across the Ni-Ni atom pairs, involving two phenolate O atoms of a Schiff base ligand, and an O–C–O moiety of a μ2-η1:η1-OAc group. The central Ni atom is located on an inversion center and has octahedral coordination involving four bridging O atoms from two Schiff base ligands in the equatorial plane and two O atoms from two μ2-η1:η1-OAc ligands in the axial positions. The coordination around the terminal Ni atoms is also octahedral, with two imino N and two phenolate O atoms from a Schiff base ligand defining the equatorial plane, and with two O atoms respectively from a μ1-η1:η0-OAc and a μ2-η1:η1-OAc ligands occupying the axial positions. The molybdenum complex has excellent catalytic property for sulfoxidation reactions.

Two mononuclear zinc(II) and manganese(II) compounds, [ZnL2] (1) and [MnL(HL)]ClO4 (2), where L is the monoanionic form of N’-(1-(pyridin-2-yl)ethylidene)isonicotinohydrazide (HL), and HL is the zwitterionic form of HL, have been prepared and characterized by elemental analyses, IR and UV-Vis spectroscopy, and single-crystal X-ray crystallographic determination. Compound 1 contains a neutral [ZnL2] complex molecule. Compound 2 contains a [MnL(HL)]+ complex cation and one perchlorate anion. The metal atoms in the complexes are in octahedral coordination. The hydrazone ligands coordinate to the metal atoms through the pyridine N, imine N, and enolate O atoms. The compounds were investigated for their antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans.