Effects of 3d-4f magnetic exchange interactions on the dynamics of the magnetization of Dy-III-M-II-Dy-III trinuclear clusters

摘要

[{Dy(hfaC)(3)}(2)(Fe(bpca)(2))}]center dot CHCl3 ([Dy2Fe]) and [{Dy(hfac)(3)}(2){Ni-(bpca)(2)}]center dot CHCl3 ([Dy2Ni]) (in which hfac(-) = 1,1,1,5,5,5-hexafluoroacetylacetonate and bpca-=bis(2-pyridylcarbonyl)amine anion) were synthesized and characterized. Single-crystal X-ray diffraction shows that [Dy2Fe] and [Dy2Ni] are linear trinuclear complexes. Static magnetic susceptibility measurements reveal a weak ferromagnetic exchange interaction between Ni-II and Dy-III ions in [Dy2Ni], whereas the use of the diamagnetic Fen ion leads to the absence of magnetic exchange interaction in [Dy2Fe]. Dynamic susceptibility measurements show a thermally activated behavior with the energy barrier of 9.7 and 4.9 K for the [Dy2Fe] and [Dy2Ni] complexes, respectively. A surprising negative effect of the ferromagnetic exchange interaction has been found and has been attributed to the structural conformation of these trinuclear complexes.