Synthesis, characterization, and density functional theory studies of hydrazone–oxime ligand derived from 2,4,6‐trichlorophenyl hydrazine and its metal complexes searching for new antimicrobial drugs

Abstract

Novel 13 mononuclear complexes derived from 3‐(2‐(2,4,6‐trichlorophenyl) hydrazono) butan‐2‐one oxime with various molar ratio, geometry and different mode of interaction were prepared using transition metal Cd2+, Zn2+, Cu2+, Ni2+, Co2+, Fe3+, Mn2+, and VO2+. The structure of these compounds was investigated physically, analytically, and spectrophotometrically. The ligation sites of the free 3‐(2‐(2,4,6‐trichlorophenyl) hydrazono) butan‐2‐one oxime were designated via molecular modeling calculations. Furthermore, quantum chemical parameters for the ligand and its complexes were calculated. The analytical and spectral data revealed that the complexes (2–13) were formed with molar ratio of (1 M:1 L) or (1 M:2 L) in which hydrazone oxime adhered with the metal ion as a univalent or neutral bidentate chelator, via the imino nitrogen atom of hydrazone moiety and oximato nitrogen atom of deprotonated/protonated oxime moiety adopting different geometrical structures. The electron spin resonance (ESR) spectra of Cu2+complexes (7–8) and (10–11) were referred to axial symmetry with g||> g┴> ge, which indicated that unpaired electron is localized in a d(x2 − y2)orbital with notable bonding covalency nature. The thermo analysis (thermogravimetry [TG]) confirmed that the complexes were decayed in one, two, three, or four steps starting with dehydration process, elimination of coordination water molecules, or removal of anions and completed with the whole decomposition of the complexes with the formation of metal oxide. The ligand did not exhibit antimicrobial activities, but its complexes showed variable activities.