Exploring the Slow Relaxation of the Magnetization in Co(III) -Decorated {Dy(III) 2 } Units

We have prepared and structurally characterized a new member of the butterfly-like {Co(III) 2 Dy(III) 2 } single-molecule magnets (SMMs) through further Co(III) decoration, with the formula [Co(III) 4 Dy(III) 2 (OH)2 (teaH)2 (tea)2 (Piv)6 ] (teaH3 =triethanolamine; Piv=trimethylacetate or pivalate). Direct current (DC) susceptibility and magnetization measurements were performed allowing the extraction of possible crystal-field parameters. A simple electrostatic modeling shows reasonable agreement with experimental data. Alternating current (AC) susceptibility measurements under a zero DC field and under small applied fields were performed at different frequencies (i.e., 10-1500 Hz) and at low temperatures (i.e., 2-10 K). Multiple magnetization relaxation pathways are observed. Comparison with previously reported {Co(III) 2 Dy(III) 2 } complex measurements allows an overall discussion about the origin of the dynamic behavior and its relationship with crystal-field split ground multiplet sublevels.