Cyanide-bridged coordination polymers constructed from lanthanide ions and octacyanometallate building-blocks†
Abstract
A new series of cyanide-bridged assemblies, {KH[Ln2(2,3-pzdc)2(CH3OH)(H2O)7][M(CN)8]}ยท5H2O (Ln3+ = Nd, Gd, Tb, and Dy; M4+ = Mo and W), were synthesised by self-assembling lanthanide ions and octacyanometallate ions in the presence of pyrazine-2,3-dicarboxylic acid (2,3-H2pzdc). These compounds have a 3D structure in which octagon-like Ln4M4(CN)8 rings are connected through a second Ln3+ center via the carboxylate groups of one 2,3-pzdc. The resulting 1D channels are filled with K+ ions and lattice water molecules. The temperature and field dependent magnetization studies as well as ab initio calculations indicate weak ferromagnetic interactions between the Gd3+ ions within the GdMo compound whilst no magnetic interactions exist in GdW analogues. The magnetic properties of Nd3+, Tb3+ and Dy3+ compounds are strongly dominated by the magnetic anisotropy of the lanthanide ions, irrespective of the octacyanometallate building-block used.