Effects of anionic co-ligands and metal salts on the synthesis, solid-state structure and biological properties of mercury(ii) complexes based on phosphorus ylide ligands

Abstract

Six new dimeric and polymeric mercury(II) complexes with compositions of [LHg(N₃)(µ-Cl)]₂ (1), [LHg(Br)(µ-Br)]₂ (2), [LHg(I)(µ-I)]₂ (3), [LHg(SCN)(µ-Cl)]₂ (4a), [LHg(SCN)(µ-SCN)]₂ (4b) and [LHg(N₃)(µ-N₃)]_n (5) (L = (4-bromobenzoyl)(triphenylphosphonio)methanide) have been synthesized and characterized using single-crystal X-ray diffraction, elemental analysis, and FT-IR and NMR spectroscopic studies. The reaction of mercury(II) chloride with L and excess sodium azide in methanol yields a dimeric chloride-bridged mercury–azide complex (1). In contrast, mercury(II) bromide and iodide form dimeric halide-bridged complexes (2 and 3), while mercury(II) acetate produces a polymeric mercury–azide complex (5). Dimeric mercury–thiocyanide complexes (4a and 4b) are synthesized similarly to complex 1, substituting KSCN for NaN₃. The results indicate that, under identical reaction conditions, azide anions act as terminal ligands, while thiocyanate functions as both bridging and terminal ligands, demonstrating that the final structures of mercury(II) complexes of phosphorus ylides are influenced by the mercury(II) salts and pseudohalide co-ligands used. Furthermore, the biological features of the synthesized mercury(II) complexes and the influence of pseudohalide ions (N₃⁻ and SCN⁻) on these features are discussed.