Antibacterial and antifungal activity of metal(II) complexes of acylhydrazones of 3-isatin and 3-(N-methyl)isatin

Cobalt(II), nickel(II), copper(II) and zinc(II) complexes of 2-thiophenecarbonyl hydrazone of 3-isatin (H2L 1 ) and 2-furoic hydrazones of 3-isatin (H2L 2 ) and 3-(N-methyl)isatin (HL 3 ), with general composition [M(L)2]� nX, where X is ethanol or/and water, were synthesised and characterised. The molecular structure of HL 3 showed that it crystallised in the keto form, which is also the more abundant tautomer for the three hydrazone ligands in solution. The three ligands behave as j 2 -O,N donors in the cobalt(II) and zinc(II) complexes. The X-ray crystal structure of pseudotetrahedral [Zn(HL 1 )2]� 1.75MeOH confirmed the O,N coordination mode of the two monodeprotonated ligands in their keto forms. Secondary interactions of zinc ions with the O atoms of each isatin keto residue provoke a substantial distortion towards a square pyramidal form. The interaction of the isatin keto residues is stronger in the three nickel(II) complexes where the three acylhydrazones can be considered as j 3 -O,N,O donors.