Nickel(II) complexes with dithiocarbamate and 1,2-bis(diphenylphosphino)ethane ligands: precursor for photocatalytically active nickel sulfide nanoparticles

Homoleptic nickel(II) complexes, namely bis(N-(3-chlorobenzyl)-N-(pyridin-3-ylmethyl)dithiocarbamato-𝜅2S,S’)nickel(II) (1) and bis(N-dodecyl-N-((thiophen-2-yl)methyl)dithiocarbamto-𝜅2S,S′)nickel(II) (2) were prepared. The reactions of 1 and 2 with 1,2-bis(diphenylphosphino)ethane resulted in the formation of analogues species, namely bis(𝜅2-P,P’-diphenylphosphinoethane)(N-(3-chlorobenzyl)-N-(pyridin-3-ylmethyl)dithiocarbamato-𝜅2S,S’)nickel(II) perchlorate (3) and bis(𝜅2-P,P’-diphenylphosphinoethane)(N-dodecyl-N-((thiophen-2-yl)methyl)dithiocarbamto-𝜅2S,S′)nickel(II) perchlorate (4), respectively. Complexes 1–4 were characterized using various spectral techniques including elemental analysis, NMR, FTIR, and UV–Vis spectroscopy. Single-crystal XRD analysis of complex 3 reveals that both ligands coordinate to the nickel center in a bidentate fashion, resulting in a distorted square planar geometry. Complex 3 demonstrates the presence of an intramolecular Ni···H–C (sp³) anagostic interaction, as confirmed by single-crystal X-ray diffraction analysis. Anticancer activity of 1 and 3 was assessed via the MTT assay. Complex 3 (IC50 = 61μM) exhibited higher activity. Complex 2 function as precursor for nickel sulfide nanoparticles using the solvothermal decomposition method. The nanoparticles were analyzed using PXRD, FESEM, and EDS. PXRD analysis revealed that solvothermal decomposition of 2 produced Ni17S18 with the hexagonal crystal structure. The nickel sulfide nanoparticles examined for photocatalytic activity had high methylene blue degradation efficiency of 75% after 90 min.