Butterfly M 2 III Er 2 (M III = Fe and Al) SMMs: Synthesis, Characterization, and Magnetic Properties

摘要

The reaction of N -(2-pyridylmethyl)iminodiethanol (H_(2)L, pmide), FeCl_(2)·4H_(2)O or AlCl_(3)·6H_(2)O with ErCl_(3)·6H_(2)O and p -Me-PhCO_(2)H in the ratio of 2:1:1:4 in the presence of Et_(3)N in MeOH and MeCN yielded compounds Fe_(2)Er_(2)(μ_(3)-OH)_(2)(pmide)_(2)(p -Me-PhCO_(2))_(6)·2MeCN (1 ) and Al_(2)Er_(2)(μ_(3)-OH)_(2)(pmide)_(2)(p -Me-PhCO_(2))_(6)·2MeCN (2 ). These two complexes are isostructural, possessing a planar butterfly motif with the Er~(III) ions in the wingtip positions. Both compounds show single molecule magnet (SMM) behavior. For the Al_(2)Er_(2) compound, the slow relaxation of the magnetization under zero applied direct current (dc) field does not show maxima, but the relaxation processes could be analyzed using an applied dc field of 1000 Oe. In-depth alternating current measurements under different dc fields on the Fe_(2)Er_(2) compound reveals that the Fe–Fe and Fe–Er interactions speed up the relaxation and decrease the energy barrier height of the SMM in comparison with the Al_(2)Er_(2) case.