Binuclear and polymeric Hg(II) complexes of an ambidentate phosphorus ylide : synthesis, crystal structure, antibacterial activity, and theoretical studies

The new alpha-keto-stabilized phosphorus ylide Ph3PCHC(O)PhCN (Y) was synthesized by addition of triphenylphosphine to 2-bromo-4 '-cyanoacetophenone, followed by treatment with NaOH 10%. Reaction of ligand (Y) with methanolic solution of mercury(II) halides under mild conditions yielded the binuclear complexes [Y center dot HgX2](2) [X=Cl (1), Br (2), I (3)]. The new organic/inorganic composite polymer [Hg(NO3)(2)(Y)](n) (4) was synthesized by the reaction of mercury(II) nitrate with the phosphorus ylide Y. Compounds synthesized were characterized by Fourier-transform infrared, H-1, P-31, and C-13 nuclear magnetic resonance spectroscopic methods, which confirmed the coordination of ylide to the metal center through the ylidic carbon atom. Single-crystal X-ray structures of phosphorus ylide Y and polymeric complex 4 were also determined and the crystallographic data of complex 4 showed that the title complex has an infinite one-dimensional structure. Furthermore, the electronic and molecular structures of complexes 1-3 were investigated at the BP86/def2-SVP level of theory, indicating an increasing trend for C -> M bond lengths: Hg2I2 > Hg2Br2 > Hg2Cl2 in [Y -> HgX2](2) (X = Cl, Br, I) complexes. In addition, the antibacterial activity of ligand Y and all complexes using the agar disc diffusion method was examined against both selected gram-positive and gram-negative bacteria. Results indicated that the ligand Y and complexes 1 and 4 show good antibacterial effect against gram-positive bacteria tested; besides, the inhibition zones of complexes were significantly larger than those of chloramphenicol as standard