Supramolecular networks of transition metal sulfates templated by piperazine

Syntheses, structural studies from single-crystal X-ray diffraction and thermal behaviour of (C4H12N2)[MII(H2O)6](SO4)2 with MII = Mn, Ni, Fe and Cu are reported. All compounds crystallise in monoclinic system, space group P21/n. The two isotypical compounds (C4H12N2)[Mn(H2O)6](SO4)2 (I) and (C4H12N2)[Ni(H2O)6](SO4)2 (II), are isostructural with the related cobalt and zinc phases, while the isotypical sulfates (C4H12N2)[Fe(H2O)6](SO4)2 (III) and (C4H12N2)[Cu(H2O)6](SO4)2 (IV) belong to another structure type. The three-dimensional structure networks for the four compounds consist of isolated [MII(H2O)6]2+ and (C4H12N2)2+ cations and (SO4)2− anions linked by hydrogen-bonds only. The thermal behaviour of the precursors has been studied by powder thermodiffractometry and thermogravimetric analyses. The first stages of dehydration are discussed with respect to the hydrogen bonds within the compounds.

Graphical abstractA series of transition metal sulfates in the presence of piperazine, (C4H12N2)[MII(H2O)6](SO4)2, were prepared and characterised. Two structural arrangements are pointed out, in which piperazine plays a templating role. The thermal behaviours are related to the nature of the metal.Figure optionsDownload full-size imageDownload as PowerPoint slide