Heterobimetallic Fe(II)–Cu(I) Complexes Supported with 1,1′-Bis(diphenylphosphino)ferrocene and Chelating Sulfur Donor Ligands: Structural Characterization, DFT Analysis, Anti-tyrosinase Assay and Biological Studies

Abstract

Heterobimetallic complexes [(dppf)CuSP(S)(OiPr)2] (1), [(dppf)CuSP(S)(OEt)2] (2), [(dppf)CuSP(S)(OCy)2] (3) and [(dppf)CuS2H2B(mt)2] (4), supported with sulfur donors from the family of dialkyldithiophosphate, SP(S)(OR)2 (R = iPr, Et, Cy) and borate ligands, (S)2H2B(mt)2, were synthesized in one pot by the reaction of 1,1′-Bis(diphenylphosphino)ferrocene (dppf) with [Cu(CH3CN)4]BF4 and subsequent addition of the chelating sulfur donor ligands at room temperature in an overall moderate yield. 1-4 were characterized using a combination of 1H, 13C{1H}, 31P{1H} NMR, IR spectroscopy techniques, and single crystal X-ray diffraction. Crystal structure analysis revealed that Cu(I) centers in 1-4 adopt a distorted tetrahedral geometry. The borate ligand in 4 adopts a κ3-S,S,H mode in the solid state. A density functional theory geometry optimization calculation was used to extract further structural and electronic information about 1-4. To investigate the possible cytotoxicity of 1-4, in vitro cellular tests were carried out on the human cancerous breast cell line MCF-7. The antibacterial activities of complexes 1 and 4 were screened against gram-positive Staphylococcus aureus PTCC 1112 and gram-negative Escherichia coli PTCC 1330.