Synthesis, characterization and H2 uptake of novel Hg(II) complexes containing 1,4-benzothiazin-3-one

Abstract

Abstract Treatment of 1,4-benzothiazin-3-one (Hbto) with mercury(II) acetate Hg(OAc)2 in 2:1 mol ratio affords [Hg(bto)2] (1) in 99% yield. The resulted complex was used as a synthon to prepare new mixed-ligand complexes with monophosphines or diphosphines of the types [Hg(bto)2(L)2] or [Hg(bto)2(L-L)]; where L = triphenylphosphine (Ph3P) (2) or triphenylphosphinesulfide (Ph3PS) (3); L-L = 1,2-bis(diphenylphosphino)ethane (dppe) (4) or 1,1′-bis(diphenylphosphine)ferrocene (dppf) (5). FTIR, 1H NMR, 13C NMR, 31P-{1H} NMR, molar conductivity and elemental analysis were used to characterize the resulted complexes. Results suggest that 'bto' ion in [Hg(bto)2] (1) is linked to mercury ion via exocyclic oxygen and endocyclic nitrogen atoms in a chelating bidentate fashion while in the complexes (2–5), it is linked to mercury ion via endocyclic nitrogen atom in a monodentate fashion. Furthermore, to take benefit of mercury complexes which were classified as toxic compounds, [Hg(bto)2] (1) complex has been evaluated for its susceptibility to hydrogen storage. The result of H2 storage showed that this complex can store 1.42 wt% of hydrogen under 88 bar and 77 K.