Heteroleptic Silver(I) and Gold(I) N‑Heterocyclic Carbene Complexes: Structural Characterization, Computational Analysis, Tyrosinase Inhibitory, and Biological Effects

Derivatization of (NHC)­M-Cl (M = Ag, Au) with selected sulfur donors from the family of dialkyldithiophosphates and bis­(2-mercapto-1-methylimidazolyl)­borate ligands gave a series of heteroleptic mononuclear complexes. In single-crystal X-ray diffraction analysis, Ag­(I) complexes adopted a trigonal planar geometry, while Au­(I) complexes are near-linear. TD-DFT and hole–electron analyses of the selected complexes gave insight into the electronic features of the metal complexes. In vitro cellular tests were conducted on the human cancerous breast cell line MCF-7 using 2 and 8. The antibacterial activities of complexes 1, 2, 3, 7, 8, and IPr–Ag-Cl were also screened against Gram-positive ( Staphylococcus aureus PTCC 1112) and Gram-negative ( Escherichia coli PTCC 1330) bacteria. Antityrosinase and hemolytic effects of the selected compounds were also determined.