New coordination polymers based on a novel polynitrile ligand:: Synthesis, structure and magnetic properties of the series [M(tcnoetOH)2(4,4′-bpy)(H2O)2](tcnoetOH-=[(NC)2CC(OCH2CH2OH) C(CN)2]-; M=Fe, Co and Ni)

A novel polynitrile anionic ligand, tcnoetOH (=[NC)(2)CCOCH(2)CH(2)OH)CCN)(2)] ), has been synthesized by a one-pot reaction from a cyclic acetal and malononitrile. This ligand has been successfully used to prepare, with 4,4'-bpy as co-ligand, a novel series of coordination polymers formulated as [MtcnoetOH) 24,4'-bpy)H(2)O)(2)] with MII) = Fe 1), Co 2) and Ni 3). These isostructural compounds present a linear chain structure consisting of octahedrally coordinated metal ions bridged by trans 4,4'-bpy ligands. The coordination sphere of the metal ions is completed with two terminal tcnoetOH ligand and two water molecules. The magnetic properties indicate that the three compounds are paramagnetic, as expected from the long 4,4'-bpy bridge connecting the metal atoms. Their magnetic properties have been fitted with a model of isolated ions including a zero field splitting for the FeII) and NiII) derivatives. (C) 2008 Elsevier B.V. All rights reserved.