Spectroscopic properties and antimicrobial activity of dioxomolybdenum(VI) complexes with heterocyclic S,S’-ligands

Abstract

Five new dioxomolybdenum(VI) complexes of the general formula[MoO2(Rdtc)2], 1-5, where Rdtc-refer to piperidine- (Pipdtc), 4-morpholine-(Morphdtc), 4-thiomorpholine-(Timdtc), piperazine- (Pzdtc) or Nmethylpiperazine- (N-Mepzdtc) dithiocarbamates, respectively, have been prepared. Elemental analysis, conductometric measurements, electronic, IR and NMR spectroscopy have been employed to characterize them. Complexes 1-5 contain a cis-MoO2 group and are of an octahedral geometry. Two dithiocarbamato ions join as bidentates with both the sulphur atoms to the molybdenum atom. The presence of different heteroatom in the piperidinо moiety influences the v(C----N) and v(C----S) vibrations, which decrease in the order of the complexes with: Pipdtc > N-Mepipdtc > Morphdtc > Pzdtc > Timdtc ligands. On the basis of spectral data, molecular structures of complexes 1-5 were optimized on semiempirical molecular-orbital level, and the geometries, as obtained from calculations, described. Antimicrobial activity was tested against nine different laboratory control strains of bacteria and two strains of yeast Candida albicans. All tested strains were sensitive. Complexes bearing heteroatom in position 4 of piperidine moiety are significantly more potent against bacteria tested comparing to corresponding ligands.

Keywords

• dithiocarbamates
• molybdenum(VI) complexes
• MoO22+ group
• geometry optimization