Two mononuclear nickel(II) complexes with Schiff base ligands: Synthesis, crystal structures, and antibacterial activities

ABSTRACTTwo new mononuclear nickel(II) complexes, [NiL1(NCS)] (1) and [Ni(L2)2]·2NO3 (2), where L1 is the deprotonated form of 1-[(2-ethylaminoethylimino)methyl]-naphthalen-2-ol, and L2 is the zwitterionic form of 2,4-dibromo-6-[(2-ethylaminoethylimino)methyl]phenol, have been prepared and characterized by physico-chemical methods and single-crystal X-ray diffraction. The Ni atoms in both complexes are in square planar coordination. The Ni atom in 1 is coordinated by one phenolate O, one imine N, and one amine N atom of L1 ligand and one thiocyanate N atom. The Ni atom in 2 is coordinated by two phenolate O and two imine N atoms of two L2 ligands. Crystals of the complexes are stabilized by hydrogen bonds. Thermal stability of the complexes has been studied. The Schiff bases and the complexes showed potent antibacterial activities.