Reaction of Dy(hfac)3·2H2O (hfac = hexafluoroacetyl acetonate) with 2-(2-hydroxyphenyl)nitronyl nitroxide (NITPhOH) and 2-(5-bromo-2-hydroxyphenyl)nitronyl nitroxide (NIT5BrPhOH) yielded [Dy2(hfac)4(NITPhO)2] 1 and [Dy2(hfac)4(NIT5BrPhO)2] 2, respectively. These compounds are phenoxo-O bridged binuclear complexes with the radical unit of a ligand coordinated to a single Dy. The Ln centers exhibit a heptacoordinated environment. Despite having very similar structures, these compounds exhibit distinct magnetic behaviors. Compound 1 shows slow relaxation of its magnetization indicating single-molecule magnet behavior, while no frequency-dependent out-of-phase signals were found for complex 2. This difference is likely to result from electronic effects induced by halogen substitution.
Dalton Transactions
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