A unique 3-D 3d-4f heterometallic coordination polymer with double betaine ligand: Crystal structure and magnetic properties

A unique 3d-4f heterometallic coordination polymer with double betaine ligand, [GdCu2(L-1)(4)(H2O2)(2)](ClO4)(7) center dot 6H(2)O 1 (L-1 = 1,3-bis(pyridinio-4-carboxylato)-propane), has been synthesized by the self-assembly of Cu(ClO4)(2) and Gd(ClO4)(3) with flexible double betaine ligand L-1, and structurally characterized by single-crystal X-ray diffraction. The structure of 1 can be regarded as being constructed by the cross-linkage of the vertex-sharing double-paddle-wheel-like trinuclear [Cu(COO)(4)Gd(COO)(4)Cu] units and L-1 ligands to produce an interesting cationic NaCl-like framework with a 4(12)6(3) topology, which is counter-balanced by the perchlorate ions located in the interspaces of the framework. Variable-temperature magnetic susceptibilities of 1 show there is no magnetic interaction between the Cu(II) and Gd(III) ions. (c) 2007 Elsevier B.V. All rights reserved.