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

Abstract

A novel polynitrile anionic ligand, tcnoetOH −(=[(NC) 2CC(OCH 2CH 2OH)C(CN) 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 [M(tcnoetOH) 2(4,4′-bpy)(H 2O) 2] with M(II) = 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 Fe(II) and Ni(II) derivatives.