AUTHOR=Kühne Irina A. , Anson Christopher E. , Powell Annie K. 

TITLE=The Influence of Halide Substituents on the Structural and Magnetic Properties of Fe6Dy3 Rings

JOURNAL=Frontiers in Chemistry

VOLUME=8

YEAR=2020

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2020.00701

DOI=10.3389/fchem.2020.00701

ISSN=2296-2646

ABSTRACT=<p>We report the synthesis and magnetic properties of three new nine-membered Fe(III)-Dy(III) cyclic coordination clusters (CCCs), with a core motif of [Fe<sub>6</sub>Dy<sub>3</sub>(μ-OMe)<sub>9</sub>(vanox)<sub>6</sub>(X-benz)<sub>6</sub>] where the benzoate ligands are substituted in the para-position with X = F (<bold>1</bold>), Cl (<bold>2</bold>), Br (<bold>3</bold>). Single crystal X-ray diffraction structure analyses show that for the smaller fluorine or chlorine substituents the resulting structures exhibit an isostructural Fe<sub>6</sub>Dy<sub>3</sub> core, whilst the 4-bromobenzoate ligand leads to structural distortions which affect the dynamic magnetic behavior. The magnetic susceptibility and magnetization of <bold>1</bold>-<bold>3</bold> were investigated and show similar behavior in the dc (direct current) magnetic data. Additional ac (alternating current) magnetic measurements show that all compounds exhibit frequency-dependent and temperature-dependent signals in the in-phase and out-of-phase component of the susceptibility and can therefore be described as field-induced SMMs. The fluoro-substituted benzoate cluster <bold>1</bold> shows a magnetic behavior closely similar to that of the corresponding unsubstituted Fe<sub>6</sub>Dy<sub>3</sub> cluster, with U<sub>eff</sub> = 21.3 K within the Orbach process. By increasing the size of the substituent toward 4-chlorobenzoate within <bold>2</bold>, an increase of the energy barrier to U<sub>eff</sub> = 36.1 K was observed. While the energy barrier becomes higher from <bold>1</bold> to <bold>2</bold>, highlighting that the introduction of different substituents on the benzoate ligand in the <italic>para</italic>-position has an impact on the magnetic properties, cluster <bold>3</bold> shows a significantly different SMM behavior where U<sub>eff</sub> is reduced in the Orbach regime to only 4.9 K.</p>