Synthesis and characterization of novel simultaneous C and O-coordinated and nitrate-bridged complexes of silver(i) with carbonyl-stabilized sulfonium ylides and their antibacterial activities

Abstract

Reaction of sulfonium ylides (Me)₂SCHC(O)C₆H₄R (R = H; m-NO₂; p-NO₂; p-OMe; p-Me and p-Br) with AgNO₃ in dichloromethane leads to various compounds. Single crystal X-ray diffraction analysis reveals that the adducts take 3 forms: (i) two-dimensional polymer, [AgNO₃(Me₂SCHC(O)C₆H₅)]_n (1), with nitrate bridges in which each nitrate coordinates to three silver atoms through two oxygen atoms and two Me₂SCHC(O)C₆H₅ ligands coordinate to silver centers through carbon atoms; (ii) cationic binuclear, [Ag(Me₂SCHC(O)C₆H₄-m-NO₂)₂]₂(NO₃)₂·2H₂O (2), in which Me₂SCHC(O)C₆H₄-m-NO₂ ligands simultaneously coordinate through both carbon and oxygen atoms with nitrate as a counter ion, and (iii) cationic mononuclear and anionic binuclear, [Ag(Me₂SCHC(O)C₆H₄-p-NO₂)₂]₂[{AgNO₃(μ-NO₃) (Me₂SCHC(O)C₆H₄-p-NO₂)}₂]·2CH₃OH (3), in which nitrate groups act as bridging as well as terminal ligands, and Me₂SCHC(O)C₆H₄-p-NO₂ ligands display C-coordination. Characterization of the obtained compounds was also performed by infrared, ¹H- and ¹³C-NMR spectroscopy and analytical data indicated a 1 : 2 stoichiometry between the silver(I) nitrate and ylide p-OMe (4) and 1 : 1 for ylides p-Me (5) and p-Br (6). In addition, the antibacterial effects of DMSO-solutions of complexes 1–6 were evaluated by the agar disc diffusion method against three Gram positive and three Gram negative bacteria. All complexes displayed antibacterial activity against these bacteria, with high levels of inhibitory potency exhibited against the Gram negative species.