title: Iron(II)-octacyanoniobate(IV) ferromagnet with T(C) 43 K.
abstract: We have synthesized the octacyanoniobate-based cyano-bridged 3D ferromagnet {[Fe(II)(H(2)O)(2)](2)[Nb(IV)(CN)(8)].4H(2)O}(n) and characterized structurally, spectroscopically (XANES/EXAFS, IR, UV-Vis, Resonance Raman, (57)Fe Mössbauer spectroscopy) and magnetically. crystallizes in the tetragonal system, space group I4/m, a = 11.989(5) A, c = 13.237(5) A, V = 1902.6(13) A(3). 3D coordination architecture comprises two types of Nb(IV)-C-N-Fe(II)(HS) (HS = high spin) linkages with Fe-N-C angles of 154.5 degrees and 167.5 degrees . The XANES/EXAFS spectra at Fe:K and Nb:K lines confirm the presence of Nb(IV)-C-N-Fe(II) linkages. Magnetic measurements reveal ferromagnetic ordering below T(c) = 43 K with some non-collinearity of Nb(IV) (S = 1/2) and Fe(II) (S = 2) magnetic moments. The molecular field model simulation reproduces well the M(T) curve and T(c) value with one average exchange coupling constant J(FeNb) = + 8.1 cm(-1).
authors.affiliation: Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060, Kraków, Poland.
authors.forename: Dawid
authors.initials: D
authors.lastname: Pinkowicz
authors.forename: Robert
authors.initials: R
authors.lastname: Podgajny
authors.forename: Robert
authors.initials: R
authors.lastname: Pełka
authors.forename: Wojciech
authors.initials: W
authors.lastname: Nitek
authors.forename: Maria
authors.initials: M
authors.lastname: Bałanda
authors.forename: Magdalena
authors.initials: M
authors.lastname: Makarewicz
authors.forename: Mariusz
authors.initials: M
authors.lastname: Czapla
authors.forename: Jan
authors.initials: J
authors.lastname: Zukrowski
authors.forename: Czesław
authors.initials: C
authors.lastname: Kapusta
authors.forename: Dariusz
authors.initials: D
authors.lastname: Zajac
authors.forename: Barbara
authors.initials: B
authors.lastname: Sieklucka