title: Two-dimensional zeolite-like network in the new caesium copper aluminate Cs2CuAl4O8.
abstract: Monoclinic dicaesium copper tetraaluminate, Cs2CuAl4O8, space group P2(1)/c, a = 8.4551 (7), b = 10.012 (1), c = 17.073 (2) Å, β = 101.643 (9)°, Z = 6, was obtained by high-temperature crystallization from a phosphate flux. Its microporous crystal structure presents the first example of double layers built from [AlO4] tetrahedra combined in 4-, 6- and 8-rings, topologically similar to those found in the ATT-type zeolites and isostructural minerals armstrongite, davanite and dalyite. These layers show a rare arrangement of three [AlO4] tetrahedra sharing one oxygen vertex. The aluminate slabs are further linked by chains of edge-sharing [CuO4] square planes to form a mixed anionic three-dimensional framework with Cs(+) cations in channels and cavities. An unusually short Cu···Cs distance of 3.166 Å is ascribed to the strong Jahn-Teller effect of Cu(2+). The magnetic subsystem demonstrates properties of an alternating antiferromagnetic chain with a gap in the spectrum of magnetic excitations.
authors.affiliation: M. V. Lomonosov Moscow State University, Leninskie Gory, GSP-1, Moscow 119991, Russian Federation.
authors.forename: Larisa
authors.initials: L
authors.lastname: Shvanskaya
authors.affiliation: M. V. Lomonosov Moscow State University, Leninskie Gory, GSP-1, Moscow 119991, Russian Federation.
authors.forename: Olga
authors.initials: O
authors.lastname: Yakubovich
authors.affiliation: Fachbereich Chemie der Universität Marburg, Hans-Meerwein-Str., Marburg D-35043, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Massa
authors.affiliation: M. V. Lomonosov Moscow State University, Leninskie Gory, GSP-1, Moscow 119991, Russian Federation.
authors.forename: Alexander
authors.initials: A
authors.lastname: Vasiliev
keywords: Jahn–Teller effect; X-ray diffraction; cuprato-aluminate; flux method; microporous compounds; quasi-one-dimensional magnetism; topology; zeolite