Diverse silver(i) sulfobenzoate coordination polymers and their recycling property as homogeneous catalyst in oxygenation of sulfide

Abstract

Four diverse silver(I) coordination polymers, namely {[Ag₃(bpmb)_2.5(2-sb)(2-Hsb)]·(0.5H₂O)}_n (1), [Ag₂(bpmb)₃(2-Hsb)₂]_n (2), {[Ag₂(bpmb)₂(3-sb)]·4H₂O}_n (3), and {[Ag(bpmb)(4-Hsb)]·2H₂O}_n (4) where bpmb is 1,4-bis(pyrazolyl-methyl)-benzene and sb is sulfobenzoate dianion, have been synthesized and fully characterized by elemental analysis, powder X-ray analysis, IR spectra, TG analysis, fluorescence study, and single crystal X-ray analysis. In these complexes, the bpmb ligand plays the role of bidentate bridge linking with silver ions, while the sb ligands display versatile coordination modes. The combination of the two ligands manages the silver ions to give rise to a variety of coordination networks in 1–4. The accessorial secondary interactions such as hydrogen bonding in complexes 1–4 and aromatic stacking in complexes 1–3 are also helpful for the extension and stabilization of the final supramolecular aggregates. Moreover, the catalytic activity to selective oxidation of methyl phenyl sulfide with H₂O₂ to sulfoxide also has been explored. Complexes 2 and 4 afforded 98% and 96% conversion with 93% and 90% selectivity for the methyl phenyl sulfoxide in 3 h at 323 K, respectively. In particular, complex 2 is a homogeneous catalyst during the catalytic reaction while it can be recovered by filtration upon cooling and then reused at least four times without losing activity, which is very rare in the oxygenation of sulfides.