Magnetization dynamics in a Dy based 2D coordination network bridged by a nitronyl nitroxide radical with a CN group

Abstract

A new family of Ln-radical coordination networks {[Ln(hfac)3]3(NIT-PhCN)2}n (Ln(III) = Gd 1, Tb 2 and Dy 3; hfac = hexafluoroacetylacetonate) was constructed by the reaction of NIT-PhCN nitronyl niroxide radical ( NIT-PhCN = 2-(4'-cyanophenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) with Ln(hfac)3 salts. The crystallographic investigations exhibit that the NIT-PhCN radical acts as a tridenate linker to connect three Ln ions via its NIT moiety and the CN group in a μ3- η1:η1:η1 fashion, giving rise to a 2D coordination network incorporating [Ln3(NIT)2] nodes featuring [Ln-NIT-Ln-NIT-Ln] motif. The magnetic study shows that the radicals are weakly ferromagnetically coupled with lanthanides, in which the magnetic exchange for the Gd derivative is determined as 1.52cm-1. Remarkably, the Dy derivative show slow relaxation of magnetization with an effective energy barrier to spin reversal of Ueff = 32K.