Magnetism‐Structures Relationship of 3,5‐Heptanedione Dy(III) SMMs Based on the Nitrogen‐Containing Auxiliary Ligand

Abstract

Two new 3, 5-heptanedione (β-diketonate) dysprosium complexes, namely, [Dy(L) 3 (phen)] (1) and [Dy(L) 3 (tmphen)] (2), have been designed and isolated by reactions of 3, 5-heptanedione with dysprosium chloride and auxiliary ligand under room temperature (L = 3, 5-heptanedione, phen = 1, 10-phenanthroline, tmphen = 3, 4, 7, 8-tetramethyl-1, 10-phenanthroline). Xray crystallographic analysis reveals that complexes 1 and 2 are mononuclear, and the Dy(III) ions are eight coordinated forming the square-anti-prismatic geometry. Complexes 1 and 2 were characterized by various means including elemental analysis, IR and UV spectroscopy. Magnetic studies indicate that both complexes 1 and 2 are single-molecule magnets (SMMs) under zero dc field. Notably, the auxiliary ligand plays an essential role in regulating their magnetism, which result in the essential magnetism difference between complexes 1 and 2.[a] S. Figure 8. The calculated easy axis (green line) of complexes 1 (left) and 2 (right) by Magellan software. Hydrogen atoms are omitted for clarity.

Assembly Studies of Two Planar Dy4 Single-Molecule Magnets

“…Magnetic susceptibilities (2–300 K), as plotted in Figure a,b, were measured under 1000 Oe for two title complexes. The χ M T values (58.85 and 58.95 cm 3 K mol –1 for 1 and 2 , respectively) at 300 K are a little larger than the theoretically calculated one for four isolated Dy(III) ions. − On cooling the sample of 1 to 90 K, the χ M T value drops slightly to 56.10 cm 3 mol –1 K with a subsequent abrupt reduction until 2 K to a minimum (25.90 cm 3 K mol –1 ). A lowering temperature for 2 from 300 to 73 K leads to a slow decrease in χ M T value to 51.56 cm 3 K mol –1 .…”