title: K2M(H2P2O7)2.2H2O (M = Ni, Cu, Zn): orthorhombic forms and Raman spectra.
abstract: The crystal structures of three isotypic orthorhombic dihydrogendiphosphates, namely dipotassium copper(II)/nickel(II)/zinc(II) bis(dihydrogendiphosphate) dihydrate, K2M(H2P2O7)2.2H2O (M = Cu, Ni and Zn), have been refined from single-crystal data. The M2+ and K+ cations are located at sites of m symmetry, and the P atoms occupy general positions. These compounds also exist in triclinic forms with very similar structural features. The structures of both forms are compared, as well as the geometry of the MO6 octahedron, which is considerably elongated towards the water molecules for M = Ni and Cu. Such elongation has not been observed among the other representatives of the family. A Raman study of the whole series K2M(H2P2O7)2.2H2O (M = Mn, Co, Ni, Cu, Zn and Mg) is reported.
authors.affiliation: Laboratoire Ingénierie des Matériaux Organométalliques et Moléculaires, Département de Chimie, Faculté des Sciences Dhar Mehraz, BP 1796 Atlas, 30000 Fès, Morocco.
authors.forename: Rachid
authors.initials: R
authors.lastname: Essehli
authors.forename: Brahim
authors.initials: B
authors.lastname: El Bali
authors.forename: Aziz
authors.initials: A
authors.lastname: Alaoui Tahiri
authors.forename: Mohammed
authors.initials: M
authors.lastname: Lachkar
authors.forename: Bouchaib
authors.initials: B
authors.lastname: Manoun
authors.forename: Michal
authors.initials: M
authors.lastname: Dusek
authors.forename: Karla
authors.initials: K
authors.lastname: Fejfarova