title: Structure and magnetism of new hybrid cobalt hydroxide materials built from decorated brucite layers.
abstract: The structure, synthesis and magnetic properties of three new complex cobalt hydroxyl oxalates are presented, showing a modification of the 2-D double layer hydroxide structure. Co(12)(OH)(18)(ox)(3)(pip) [ox = oxalate, C(2)O(4)(2-); pip = piperazine, C(4)N(2)H(10)] (1), is essentially built from brucite-like layers with a one ninth depletion of the octahedral sites and a preservation of a trigonal crystallographic symmetry. ACo(28)(OH)(43)(ox)(6)Br(2)(H(2)O)(2) [A = Na (2), K (3)] are similarly composed of a brucite-like layer with three nineteenths depletion of octahedral sites, again preserving a trigonal symmetry. Both 2 and 3 show a small degree of structural disorder within the framework. All of these compounds have alternating layers of a mineral-like metal hydroxide structure and a metal oxalate coordination network, with the depletion in the hydroxyl layers being templated by the coordination network. Magnetic studies of 1 reveal a metamagnetic character, with the onset of an antiferromagnetic phase below T(c) = 23.5 K (H = 0 G), and a first order antiferromagnet to metamagnet transition at H(c) = 500-1000 G (T = 20-6 K). Compound 3 shows a more conventional ferrimagnetic ordering below 33(±1) K with a small coercive field of 107(±5) G at 10 K.
authors.affiliation: WestCHEM, School of Chemistry, University of Glasgow, Glasgow, United Kingdom G12 8QQ.
authors.forename: Tony D
authors.initials: TD
authors.lastname: Keene
authors.forename: Mark E
authors.initials: ME
authors.lastname: Light
authors.forename: Michael B
authors.initials: MB
authors.lastname: Hursthouse
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Price