Capping N‐Donor Ligands Modulate the Magnetic Dynamics of DyIII β‐Diketonate Single‐Ion Magnets with D4d Symmetry. Issue 15 (29th January 2019) - Cen, Peipei
Abstract: A family of four mononuclear Dy III β‐diketonate complexes with formulas [Dy(tmhd)3 (Br2 ‐bpy) (1), [Dy(tmhd)3 (Br‐bpy)] (2 ), [Dy(tmhd)3 (dppz)] (3 ), and [Dy(tmhd)3 (mcdpq)] (4 ) (tmhd=2, 2, 6, 6‐tetramethyl‐3, 5‐heptanedione, Br2 ‐bpy=5, 5′‐dibromo‐2, 2′‐bipyridine, Br‐bpy=5‐bromo‐2, 2′‐bipyridine, dppz=dipyrido [3, 2‐ a :2′, 3′‐c]phenazine, mcdpq=2‐methoxyl‐3‐cyanodipyrido[3, 2‐ f :2, 3′‐h]quinoxaline) were prepared by modifying the capping N‐donor coligands. Dy III centers in these complexes feature an N2 O6 octacoordinate environment with distorted square‐antiprismatic D 4 d symmetry. Magnetic investigations evidenced single‐ion magnet behavior in all complexes with energy barriers U eff of 42.10 (1 ), 61.47, (2 ), 77.53 (3 ), and 2.51 K (4 ) in the absence of static field, as well as 206.03 (1 ), 224.13 (2 ), 247.76 (3 ), and 49.70 K (4 ) under applied dc field ( H dc =1500 Oe for1 and2 ; H dc =1200 Oe for3 and4 ). The different natures of the N‐donor ligands induce changes in both the coordination geometry and their intermolecular interactions, which severely impact their magnetic dynamics. The disparities in their magnetic behaviors and the uniaxial anisotropies are also explained and substantiated by theoretical calculations. Abstract : Cap variations : A combination of electron‐donating β‐diketonate ligands and different capping N‐donor coligands led to a family of four mononuclear Dy III complexes exhibiting nearly identical D 4 d symmetry but differing magnetic dynamics, which were elucidated by a combination of magnetic investigations and ab initio calculations.