Hydroxyacetone derived N4-methyl substituted thiosemicarbazone: Syntheses, crystal structures and spectroscopic characterization of later first-row transition metal complexes

Abstract

The present work reports the syntheses, crystal structures and spectroscopic characterization of later first-row transition metal complexes of hydroxyacetone derived N4-methyl substituted thiosemicarbazone. The molecular structures of Co(II) and Ni(II) complexes are determined by single crystal X-ray diffraction method. The crystal structures reveal that the Co(II) and Ni(II) complexes have crystallized in monoclinic and triclinic crystal systems with C2/c and P-1 space groups, respectively. The ligand, 1-(1-hydroxypropan-2-ylidene)-N4-methylthiosemicarbazone ligates in a neutral, SNO tridentate fashion to the central metal ions. The numerous physicochemical investigations carried out to the synthesized complexes disclose the metal to ligand stoichiometry to be 1:2 in Co(II), Ni(II) and Zn(II) complexes whereas 1:1 in Cu(II) complex. The ligand environment forms a distorted octahedral geometry around Co(II), Ni(II) and Zn(II) metal centers, while square pyramidal geometry over Cu(II) ion. The in vitro antitubercular results against Mycobacterium tuberculosis affirm that the synthesized compounds are four-fold more active than the standard drug, Streptomycin and two-fold more active than the other two standards used, Pyrazinamide and Ciprofloxacin.