Structure and magnetism of heptanuclear complex self-assembled by the encapsulation of hexacyanoferrate with copper(II) cations of tridentate ligands

A new heptanuclear compound [(Cu(DPA)(H2O)CN)(4)(Cu(DPA)CN)(2)Fe][PF6](8)center dot 4H(2)O (1) (DPA = bis(pyridin-2-ylmethyl)amine) was synthesized by the reaction of [(Cu(DPA)](2+) unit and K3Fe(CN)(6). The cyanometalate core is encapsulated by mononuclear copper moieties via each cyanide, and Fe(III) is reduced to Fe(II). 1 crystallizes in triclinic space group P-1 with a = 13.414(6) angstrom, b = 16.254(6) angstrom, c = 16.418(6) angstrom, alpha = 117.98(4)degrees, beta = 94.49(3)degrees, gamma = 107.61(4)degrees and Z = 1. Variable temperature magnetic measurements have demonstrated that very weak ferromagnetic interaction between the nearest paramagnetic Cull centers is exhibited. Thus weak ferromagnetic coupling might be transferred by -NC-Fe-CN- bridging units. (C) 2011 Elsevier B.V. All rights reserved.