Syntheses, Crystal Structures, and Magnetic Properties
of Two <i>p</i>-<i>tert</i>-Butylsulfonylcalix[4]arene
Supported Cluster Complexes with a Totally Disordered Ln<sub>4</sub>(OH)<sub>4</sub> Cubane Core
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Abstract
Two new sandwich calix[4]arene-supported cluster complexes,
[Ln<sub>4</sub>(OH)<sub>4</sub>(TBSOC)<sub>2</sub>(H<sub>2</sub>O)<sub>4</sub>(CH<sub>3</sub>OH)<sub>4</sub>]·4H<sub>2</sub>O (H<sub>4</sub>TBSOC = <i>p</i>-<i>tert</i>-butylsulfonylcalix[4]arene; Ln = Dy, <b>1</b>; Ln = Ho, <b>2</b>), have been prepared and characterized. An X-ray crystallographic
study reveals that both complexes contain a holistically disordered
[Ln<sub>4</sub>(OH)<sub>4</sub>]<sup>8+</sup> cubane cluster core,
which is sandwiched between two antiparallel calixarene macrocycles.
Magnetic investigations indicate that complex <b>1</b> displays
slow magnetization relaxation typical for single-molecule magnets
in the absence of a static applied dc field, with the Δ<i><i>E</i>/k</i><sub>B</sub> parameter of 22.9 K, the
largest value for the calixarene-supported pure 4f single-molecule
magnets so far, whereas complex <b>2</b> does not show any relaxation
of the magnetization above 2 K
