A {Co₄O₄} Cubane Incorporated within a Polyoxoniobate Cluster

Abstract

A novel octacobalt-containing polyoxoniobate, Na6 K12 [H2 Co8 O4 (Nb6 O19 )4 ]⋅39 H2 O, has been prepared by a combination of hydrothermal and diffusion methods. The polyanion [H2 Co8 O4 (Nb6 O19 )4 ](18-) incorporates a tetrameric assembly of Lindqvist-type [Nb6 O19 ](8-) fragments trapping a {Co(II) 4 Co(III) 4 } cluster which comprises a central {Co(III) 4 O4 } cubane core, surrounded by another four Co(II) ions linkers. Furthermore, magnetic measurements show that the compound exhibits antiferromagnetic interactions.