Tetranuclear Ag(i) and Au(i) nano-sized [L2(R)8 → M4]4+ (M = Ag(i) and Au(i); R = C2H5, CH3, H, F, Cl, Br, Ph and SiH3) complexes: nature and cooperativity of metal–ligand bonds

Abstract

NHC ligands are able to stabilize different metals in different oxidation states and coordination geometries, making them interesting candidates for the synthesis of potent metal-based anti-cancer agents. This study explores the bonding characteristics and nature of cooperativity in tetranuclear cationic complexes of Ag(I) and Au(I), formulated as [L₂(R)₈ → M₄]⁴⁺ (M = Ag(I) and Au(I); R = C₂H₅, CH₃, H, F, Cl, Br, Ph and SiH₃), with potential antibacterial and anticancer properties using DFT calculations at the PBE-D3-B3LYP/def2-SVP//PBE-D3/def2-TZVP level. Bond cooperativity, evaluated through interaction energies, and the resulting data indicated that there is an anti-cooperativity behavior among the metal–ligand interactions. EDA results confirm that electrostatic contributions are found to be dominant, suggesting that the C_NHC → M bonds in these complexes are primarily electrostatic in nature.