Cu(ii)–Dy(iii) and Co(iii)–Dy(iii) based single molecule magnets with multiple slow magnetic relaxation processes in the Cu(ii)–Dy(iii) complex†
Two dinuclear Schiff-base complexes [CuIIDyIII] and [CoIIIDyIII] have been synthesized and structurally characterized. The AC susceptibility measurements taken at BDC = 0.2 T show a slow magnetic relaxation typical for single-molecule magnets. Unusual is the presence of three relaxation branches in [CuIIDyIII]; the slowest (low-frequency) process possesses the barrier to spin reversal of U/kB = 2.8 K and an extrapolated relaxation time as slow as τ0 = 0.11 s. The intermediate-frequency process is typical for SMM of this class with U/kB = 122 K and τ0 = 9.9 × 10−7 s; an onset of the high-frequency process is evidenced and this is the fastest. In contrast, the [CoIIIDyIII] complex free of exchange coupling exhibits only a single relaxation path with SMM parameters U/kB = 113 K and τ0 = 7.0 × 10−9 s.