Slow magnetic relaxation and antiferromagnetic ordering in a one dimensional nitronyl nitroxide-Tb(III) chain

Reaction of the nitronyl nitroxide radical NIT-3Brthien with Ln(hfac)(3) affords two one-dimensional lanthanide-nitronyl nitroxide compounds [Ln(hfac)(3)(NIT-3Brthien)] (Ln = Gd(III) 1, Tb(III) 2; NIT-3Brthien = 2-(3'-bromo-2'-thienyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide). Single crystal X-ray crystallographic analysis reveals that both compounds are composed of linear chains built up by Ln(hfac)(3) units bridged by NIT-5Brthien radicals through their NO groups. DC magnetic measurements reveal that the Gd complex is paramagnetic above 2.0 K, while the Tb complex orders antiferromagnetically at 4.0 K. Moreover, complex 2 possesses frequency-dependence of ac magnetic susceptibilities. The magnetic behavior of complex 2 is unique and exhibits the coexistence of slow magnetic relaxation, metamagnetism and antiferromagnetic three-dimensional magnetic ordering.