Tuning single-molecule magnetism in Dy3+ complexes via a tris(aryl)alkoxide ligand

Abstract

We report the synthesis, structures, and magnetic properties of two Dy³⁺ complexes supported by a tripodal tris(aryl)alkoxide ligand (Me₂NCH₂-o-C₆H₄)₃CO⁻. The mononuclear complex [κ³-O,N,N-(Me₂NCH₂-o-C₆H₄)₃CO]DyCl₂(THF) (1) adopts a distorted octahedral geometry, while its reaction with a dipotassium dicarbollide K₂[7,8-Me₂C₂B₉H₉] affords a heterobimetallic coordination polymer {[K(μ-Cl)Dy(κ³-O,N,N-(Me₂NCH₂-o-C₆H₄)₃CO)(μ-2,3-Me₂C₂B₉H₉)]·0.5THF}_n (2·0.5THF) featuring a layered structure. Both compounds exhibit single-molecule magnet (SMM) behavior, with effective barriers of 344 K (240 cm⁻¹) for 1 and 133 K (92.5 cm⁻¹) for 2. Ab initio calculations indicate that 1 relaxes via the third excited Kramers doublet (KD), while 2 likely relaxes through the second KD. The relaxation pathways observed experimentally for 2 do not correspond to the computed KDs, possibly due to experimental limitations at high temperatures or fast relaxation rates undetectable by alternating current susceptibility.