Synthesis, crystal structure and magnetic properties of a novel mixed-valence copper phosphonate: Na2Cu15(hedp)6(OH)2(H2O) (hedp = 1-hydroxyethylidenediphosphonate)
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Abstract
A new pillared layered mixed-valence copper phosphonate Na2Cu15(hedp)6(OH)2(H2O), where hedp represents 1-hydroxyethylidenediphosphonate anion, has been hydrothermally synthesized and structurally determined. Crystal data: trigonal, space group P, a = b = 11.720(2), c = 9.531(1) Å, U = 1134(2) Å3, Z = 1. The structure consists of honeycomb layers of edge-sharing (CuII3O)O3 units (sheet A) and edge-sharing NaO6 octahedra and CuIIO4 planes (sheet B). The layers are pillared alternately through 18-membered rings which are made up from the organic backbone of the diphosphonate groups and the CuIO2 units. A three-dimensional framework is thus formed which contains intersecting channels where the H2O molecules reside. The magnetic properties of the compound have been investigated. No long-range ordering has been found down to 2 K.