Two-dimensional Co-Ln networks bridged by phenyl pyrimidyl substituted nitronyl nitroxides: structural and magnetic properties.

Abstract

Two-dimensional hetero-tri-spin 2p-3d-4f coordination polymers involving Co(ii) and Ln(iii) ions assembled with a polydentate paramagnetic nitronyl nitroxide ligand are reported. [Ln(hfac)3{Co(hfac)2}2(NITPhPyrim)2] (LnIII = Gd 1, Tb 2; hfac = hexafluoroacetylacetonate, NITPhPyrim = 2-[4-(5-pyrimidyl)phenyl]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) consists of a two-dimensional network in which the NITPhPyrim ligand is coordinated to the metal ions by means of its pyrimidine and aminoxyl (NO) groups. In the layer, the Tb center interacts with two NO groups from two different radical ligands, and each pyrimidine connects two Co(hfac)2 units through its two nitrogen atoms to form one-dimensional Co(ii) arrays. The magnetic behavior of the two compounds results from concomitant ferro- and antiferromagnetic interactions between the spin carriers and the spin-orbit effect from Co(ii) as revealed by modeling performed for the Gd(iii) derivative.