Supramolecular structure of ammonium polyoxoarsenates(iii)

Abstract

Five novel inorganic–organic hybrids have been synthesized and characterised by single-crystal diffraction experiments. The inorganic component comprises polyoxoarsenite chain and the organic one diverse ammonium cations. The crystal structures of ammonium metaoxoarsenate(III) (1), ethylenediammonium metaoxoarsenate(III) (2), benzylammonium metaoxoarsenate(III) (3), methylammonium metaoxoarsenate(III) (4) and ethanolammonium metaoxoarsenate(III) (5) are reported and their supramolecular organisation uncovered. 1D hydrogen bonded cation–anion structural units are formed in all five compounds and it is shown that (AsO⁻₂)_n chains act as structure-directing motifs. The polyoxoarsenite chains are spanned by a series of O⋯H–N–H⋯O hydrogen bridges via ammonium cations and stiffened by secondary As⋯O interactions, comprising the primary structure. The electroneutral chains are connected by N–H⋯O hydrogen bonds into layers of secondary structure. These layers are joined to form a 3D tertiary structure by a variety of linkers ranging from hydrogen bonds, van der Waals and C–H⋯π interactions to covalent bridges.