Family of Mixed 3d–4f Dimeric 14-Metallacrown‑5 Compounds: Syntheses, Structures, and Magnetic Properties
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Abstract
An
isomorphous family of mixed 3d–4f dodenuclear aggregates,
{[Mn<sup>III</sup><sub>8</sub>Ln<sub>4</sub>(Clshi)<sub>8</sub>(OAc)<sub>6</sub>(μ<sub>3</sub>-OCH<sub>3</sub>)<sub>2</sub>(μ<sub>3</sub>-O)<sub>2</sub>(CH<sub>3</sub>OH)<sub>12</sub>(H<sub>2</sub>O)<sub>2</sub>]·4CH<sub>3</sub>OH·<i>x</i>H<sub>2</sub>O)} (where Ln = Eu<sup>III</sup> (<b>1</b>), Gd<sup>III</sup> (<b>2</b>), Tb<sup>III</sup> (<b>3</b>), and
Dy<sup>III</sup> (<b>4</b>); ClshiH<sub>3</sub> = 5-chlorosalicylhydroxamic
acid; <i>x</i> = 5 for <b>1</b> and <b>3</b>; <i>x</i> = 6 for <b>2</b>; <i>x</i> =
2 for <b>4</b>), were synthesized and characterized. They were
obtained from the reaction of ClshiH<sub>3</sub> with Mn(OAc)<sub>2</sub>·4H<sub>2</sub>O and Ln(NO<sub>3</sub>)<sub>3</sub>·6H<sub>2</sub>O. These isomorphous mixed 3d–4f compounds represent
a family of novel structures with lanthanide ions in the metallacrown
(MC) ring. Each dodecanuclear aggregate contains two offset stacked
14-MC-5 units with M–N–O–M–N–O–Ln–O–N–M–O–N–M
connectivity to capture one Ln<sup>III</sup> ion in the core of each
MC. Two 14-MC-5 units are connected through O ions with four Mn ions
and six O atoms arranged in a double Mn<sub>4</sub>O<sub>6</sub> cubane.
Magnetic measurement indicates that antiferromagnetic interactions
are present between the metal ions. The Dy<sup>III</sup> analogue
with high anisotropy and large spin shows slow magnetization relaxation
at a direct-current field of 2 kOe
