Octahedral Ni(II) and Cu(II) complexes with a new hexadentate (NSN)2 donor ligand: Synthesis, characterization, X-ray structure and DFT calculations

Abstract

Coupling of arylthioether diazonium salts with acetylacetone in NaOH medium produced the hexadentate ligand HL. This ligand can undergo keto-enol tautomerism in solution. It acts as a monoanionic hexadentate (N,S,N,N,S,N) chelator and forms 1:1 isostructural complexes, [Ni(L)](ClO4) (1) and [Cu(L)](ClO4) (2), with Ni(II) and Cu(II) respectively. The complexes have been characterized by spectral analysis. The pseudo octahedral geometries of the complexes are confirmed by single crystal X-ray diffraction studies. The X-ray and spectral characterizations confirmed the existence of the keto form of the ligand in the complexes. The electronic structures and spectral properties of the ligand and the complexes have been explained by DFT and TDDFT calculations.