title: Crystal structure and spin-trimer magnetism of Rb2.3(H2O)0.8Mn3[B4P6O24(O,OH)2].
abstract: The novel borophosphate Rb2.3(H2O)0.8Mn3[B4P6O24(O,OH)2] was prepared under hydrothermal conditions at 553 K. Its crystal structure was determined using single-crystal X-ray diffraction data obtained from a non-merohedral twin and refined against F2to R = 0.057. The compound crystallizes in the orthorhombic space group Pbcn, with unit-cell parameters a = 20.076(2) Å, b = 9.151(1) Å, c = 12.257(1) Å, V = 2251.8(2) Å3, and Z = 4. The title compound is the first example of a borophosphate with manganese ions adopting both octahedral and tetrahedral coordinations. Its unique crystal structure is formed by borophosphate slabs and chains of Mn2+-centered polyhedra sharing edges and vertices. These 2D and 1D fragments interconnect into a framework with open channels that accommodate Rb+cations and water molecules. Topological relationships between borophosphates built from three-membered rings of two borate and one phosphate tetrahedra sharing oxygen vertices, amended by additional PO4and HPO4tetrahedra, are discussed. The temperature dependence of the magnetic susceptibility of Rb2.3(H2O)0.8Mn3[B4P6O24(O,OH)2] reveals predominant antiferromagnetic exchange interactions and the high-temperature effective magnetic moment corresponding to the high-spin S = 5/2 state of Mn2+ions. At 12.5 K, a magnetic transition is evidenced by ac-susceptibility and specific heat measurements. A spin-trimer model with the leading exchange interaction J ∼ 3.2 K is derived from density-functional band-structure calculations and accounts for all experimental observations.
authors.affiliation: M.V. Lomonosov Moscow State University, Moscow 119991, Russia. vasil@mig.phys.msu.ru.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Yakubovich
authors.affiliation: M.V. Lomonosov Moscow State University, Moscow 119991, Russia. vasil@mig.phys.msu.ru and National University of Science and Technology "MISiS", 119049 Moscow, Russia.
authors.forename: Larisa V
authors.initials: LV
authors.lastname: Shvanskaya
authors.affiliation: M.V. Lomonosov Moscow State University, Moscow 119991, Russia. vasil@mig.phys.msu.ru.
authors.forename: Galina V
authors.initials: GV
authors.lastname: Kiriukhina
authors.affiliation: M.V. Lomonosov Moscow State University, Moscow 119991, Russia. vasil@mig.phys.msu.ru.
authors.forename: Anatoly S
authors.initials: AS
authors.lastname: Volkov
authors.affiliation: M.V. Lomonosov Moscow State University, Moscow 119991, Russia. vasil@mig.phys.msu.ru.
authors.forename: Olga V
authors.initials: OV
authors.lastname: Dimitrova
authors.affiliation: M.V. Lomonosov Moscow State University, Moscow 119991, Russia. vasil@mig.phys.msu.ru.
authors.forename: Evgeny A
authors.initials: EA
authors.lastname: Ovchenkov
authors.affiliation: Experimental Physics VI, Center for Electronic Correlations and Magnetism, Institute of Physics, University of Augsburg, D-86135 Augsburg, Germany and National Institute of Chemical Physics and Biophysics, 12618 Tallinn, Estonia.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Tsirlin
authors.affiliation: National University of Science and Technology "MISiS", 119049 Moscow, Russia.
authors.forename: Alexander A
authors.initials: AA
authors.lastname: Shakin
authors.affiliation: M.V. Lomonosov Moscow State University, Moscow 119991, Russia. vasil@mig.phys.msu.ru and National University of Science and Technology "MISiS", 119049 Moscow, Russia and Institute of Physics and Technology, Ural Federal University, 620002 Ekaterinburg, Russia.
authors.forename: Olga S
authors.initials: OS
authors.lastname: Volkova
authors.affiliation: M.V. Lomonosov Moscow State University, Moscow 119991, Russia. vasil@mig.phys.msu.ru and National University of Science and Technology "MISiS", 119049 Moscow, Russia and Institute of Physics and Technology, Ural Federal University, 620002 Ekaterinburg, Russia.
authors.forename: Alexander N
authors.identifier: http://orcid.org/0000-0002-7369-4424
authors.initials: AN
authors.lastname: Vasiliev