A New {Dy-5} Single-Molecule Magnet Bearing the Schiff Base Ligand N-Naphthalidene-2-amino-5-chlorophenol

作者：Alexandropoulos, Dimitris I.; Alaimo, Alysha A.; Sun, Di; Stamatatos, Theocharis C.^*

来源：Magnetochemistry, 2018, 4(4): 48.

DOI：10.3390/magnetochemistry4040048

• dysprosium
• schiff bases
• cluster compounds
• single-molecule magnets
• crystal structures

A new {Dy-5} cluster compound has been synthesized and structurally characterized from the initial use of the Schiff base ligand N-naphthalidene-2-amino-5-chlorophenol (nacpH(2)) in coordination chemistry. The 1:1 reaction between Dy(hpd)(3)center dot 2H(2)O and nacpH(2), in a solvent mixture comprising CH2Cl2 and MeOH, afforded orange crystals of [Dy-5(OH)(2)(hpd)(3)(nacp)(5)(MeOH)(5)] (1) in 70% yield, where hpd(-) is the anion of 3,5-heptadione. The {Dy-5} complex can be described as two vertical {Dy-3(mu 3-OH)}(8+) triangles sharing a common vertex; such a metal topology is unprecedented in 4f-metal cluster chemistry. Direct current (dc) magnetic susceptibility studies revealed the presence of some weak ferromagnetic exchange interactions between the five Dy-III ions at low temperatures. Alternating current (ac) magnetic susceptibility measurements at zero applied dc field showed that complex 1.3MeOH center dot CH2Cl2 exhibits temperature-and frequency-dependent out-of-phase signals below similar to 20 K, characteristics of a single-molecule magnet (SMM). The resulting relaxation times were used to construct an Arrhenius-type plot and determine an effective energy barrier, U-eff, of 100 K for the magnetization reversal. The application of a small dc field of 200 Oe resulted in the surpassing of the quantum tunneling process and subsequently the increase of the U-eff to a value of 170 K. The reported results are part of a long-term program aiming at the preparation of structurally and magnetically interesting lanthanide complexes bearing various Schiff base chelating/bridging ligands.

• 出版日期2018-12
• 单位山东大学