title: Metamagnetism in cobalt phosphates with pillared layer structures: [Co3(pyz)(HPO4)2F2] and [Co3(4,4'-bpy)(HPO4)2F2].xH2O.
abstract: Two new cobalt phosphates, [Co(3)(pyz)(HPO(4))(2)F(2)] (1) and [Co(3)(4,4'-bpy)(HPO(4))(2)F(2)].xH(2)O (x approximately 0.7) (2), have been synthesized by hydrothermal methods in the presence of aromatic amines, and characterized by single-crystal X-ray diffraction and magnetic susceptibility. Their structures consist of neutral sheets of fluorinated cobalt phosphate which are pillared through pyrazine and 4,4'-bipyridine molecules to form 3D frameworks. The structures are related to that of the mineral lazulite. Both compounds show long-range antiferromagnetic ordering below 15 K and metamagnetic behaviors. Compound 1 reveals a two-step magnetic phase transition. Crystal data for 1: monoclinic, space group C2/c (No. 15), a = 21.809(4) A, b = 7.370(1) A, c = 7.395(1) A, beta = 103.753(3) degrees, and Z = 4. Crystal data for 2 are the same as those for 1 except a = 29.940(2) A, b = 7.4421(5) A, c = 7.4170(5) A, and beta = 93.444(1) degrees.
authors.affiliation: Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan, ROC.
authors.forename: Wei-Kuo
authors.initials: WK
authors.lastname: Chang
authors.forename: Ray-Kuang
authors.initials: RK
authors.lastname: Chiang
authors.forename: Yau-Chen
authors.initials: YC
authors.lastname: Jiang
authors.forename: Sue-Lein
authors.initials: SL
authors.lastname: Wang
authors.forename: Shang-Fan
authors.initials: SF
authors.lastname: Lee
authors.forename: Kwang-Hwa
authors.initials: KH
authors.lastname: Lii