title: Ax(H3O)2-xMn5(HPO3)6 (A = Li, Na, K and NH4): open-framework manganese(ii) phosphites templated by mixed cationic species.
abstract: Ax(H3O)2-xMn5(HPO3)6 (A = Li, x = 0.55 (1-Li); A = Na, x = 0.72 (2-Na); A = K, x = 0.30 (3-K); A = NH4, x = 0.59 (4-NH4)) phases were synthesized by employing mild hydrothermal conditions. 1-Li was studied by single crystal X-ray diffraction, while sodium, potassium and ammonium containing analogues were obtained as polycrystalline samples and characterized by powder X-ray diffraction. The four compounds were characterized by ICP-Q-MS, thermal analysis and XPS, IR, UV/Vis and EPR spectroscopy. Single crystal data indicate that 1-Li crystallizes in the P3[combining macron]c1 space group with lattice parameters a = 10.3764(1) Å and c = 9.4017(1) Å with Z = 2. The crystal structure of these phases is constituted by a three-dimensional [Mn(ii)5(HPO3)6](2-) anionic skeleton templated by alkali metal and ammonium cations together with protonated water molecules. Such an inorganic framework is formed by layers of edge-sharing MnO6 octahedra placed in the ab plane and joined along the c direction through phosphite pseudotetrahedra. The sheets display 12-membered ring channels parallel to the c-axis, ca. 5 Å in diameter, where the extraframework species display a strong disorder. EPR measurements point to the existence of short range ferromagnetic interactions around 12 K. Magnetic susceptibility and heat capacity measurements show that all the compounds exhibit long range antiferromagnetic order below circa 4 K, with a significant magnetocaloric effect around the Neel temperature.
authors.affiliation: Departamento de Ciencia de los Materiales, FCFM, Universidad de Chile, Av. Beauchef 851, Santiago 8370448, Chile. joseba.orive@ing.uchile.cl.
authors.forename: Joseba
authors.initials: J
authors.lastname: Orive
authors.affiliation: Departamento de Mineralogía y Petrología, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV/EHU), Apdo. 48940 Leioa, Spain. roberto.fernandez@ehu.eus maribel.arriortua@ehu.es and Basque Center for Materials, Applications & Nanostructures (BC Materials) Parque Tecnológico de Zamudio, Camino de Ibaizabal, Edificio 500 - 1°, 48160 Derio, Spain. roberto.fernandez@bcmaterials.net maribel.arriortua@ehu.es.
authors.forename: Roberto
authors.initials: R
authors.lastname: Fernández de Luis
authors.affiliation: CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander, Spain. rodrigufj@unican.es.
authors.forename: Jesús Rodríguez
authors.initials: JR
authors.lastname: Fernández
authors.affiliation: Basque Center for Materials, Applications & Nanostructures (BC Materials) Parque Tecnológico de Zamudio, Camino de Ibaizabal, Edificio 500 - 1°, 48160 Derio, Spain. roberto.fernandez@bcmaterials.net maribel.arriortua@ehu.es and Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV/EHU), Apdo. 48940 Leioa, Spain. luis.lezama@ehu.es.
authors.forename: Luis
authors.initials: L
authors.lastname: Lezama
authors.affiliation: Departamento de Mineralogía y Petrología, Facultad de Ciencia y Tecnología, Universidad del País Vasco (UPV/EHU), Apdo. 48940 Leioa, Spain. roberto.fernandez@ehu.eus maribel.arriortua@ehu.es and Basque Center for Materials, Applications & Nanostructures (BC Materials) Parque Tecnológico de Zamudio, Camino de Ibaizabal, Edificio 500 - 1°, 48160 Derio, Spain. roberto.fernandez@bcmaterials.net maribel.arriortua@ehu.es.
authors.forename: María I
authors.initials: MI
authors.lastname: Arriortua