Syntheses, characterization, and antimicrobial properties of nickel(II) dithiocarbamate complexes containing NiS₄ and NiS₂PN moieties

Abstract

Three Ni(II) dithiocarbamate complexes, [Ni(buphdtc)₂] (1), [Ni(buphdtc)(PPh₃)(NCS)] (2) and [Ni(buphdtc)(PPh₃)(NC)] (3) (where bu = butyl and ph = phenyl), were synthesized and characterized by elemental analysis, UVvis, and FTIR spectroscopies. Complexes 1 and 2 were further characterized by single-crystal X-ray structural analysis. The single-crystal X-ray structural analysis indicates a slightly distorted square planar geometry. In 2 and 3, the influences of the auxiliary ligands (PPh₃, NCS, and NC) on their steric and electronic properties were observed. Thermal studies of the complexes showed decomposition starting at 250–300 °C, leading to formation of nickel sulfide phases around 400 °C. The complexes were screened against some bacteria strains, Staphylococcus aureus, Streptococcus pneumoniae, Bacillus subtilis, Escherichia coli, Klebsiella oxytoca and Pseudomonas aeruginosa, and two fungi species, Aspergillus niger and Fusarium oxysporum. The complexes showed moderate-to-strong antimicrobial potentials, with [Ni(buphdtc)₂] (1) displaying the best antimicrobial activity. Fluconazole and streptomycin were used as reference drugs for antifungal and antibacterial assays, respectively.

Keywords:

• Nickel(II) complexes
• X-ray crystal structure
• thermal stability
• antimicrobial properties

Acknowledgements

The authors gratefully acknowledge the financial support of North-West University.