Bis-phenoxido and bis-acetato bridged heteronuclear {CoIIIDyIII} single molecule magnets with two slow relaxation branches†
Abstract
Two bis-μ-phenoxido–bis-μ-acetato heterobimetallic {CoIIIDyIII} complexes 1 and 2, formulated as [CoIIIDyIIIL(μ-OAc)2(NO3)2] derived from the comparable hexadentate Schiff bases N,N′-ethylenebis(3-ethoxysalicylaldimine) and N,N′-ethylenebis(3-methoxysalicylaldimine) were synthesized and X-ray structure analysis confirms their nearly identical structures. These are the first examples of bis(μ-phenoxido)–bis(μ-carboxylato) {CoIIIDyIII} systems. The AC susceptibility measurements show that both complexes exhibit a field-induced slow magnetic relaxation with two relaxation branches. While the high-frequency process spans the usual range of the relaxation time for analogous single molecule magnets (τ0 ∼ 10−7 s), the low-frequency branch is as slow as τ ∼ 0.1 s at T = 1.9 K and B = 0.2 T.