AUTHOR=Agapaki Eleftheria , Charkiolakis Emmanouil K. , Nichol Gary S. , Gracia David , Evangelisti Marco , Brechin Euan K. 

TITLE=Magnetocaloric effect in a high-spin ferromagnetic molecular cluster

JOURNAL=Frontiers in Chemistry

VOLUME=12

YEAR=2024

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2024.1494609

DOI=10.3389/fchem.2024.1494609

ISSN=2296-2646

ABSTRACT=<p>The reaction of MnCl<sub>2</sub>·4H<sub>2</sub>O with HL ((1-methyl-1H-imidazol-2-yl)methanol) and pdH<sub>2</sub> (1, 3 propanediol) in a basic MeCN solution results in the formation of a mixed-valence [Mn<sub>20</sub>] cationic cluster and two [Mn<sup>II</sup>Cl<sub>4</sub>] counter anions. The metallic skeleton of the cluster describes two geometrically equivalent mixed-valent, linked [Mn<sup>III</sup><sub>6</sub>Mn<sup>II</sup><sub>4</sub>] supertetrahedra in which nearest-neighbor metal ions have a different oxidation state. Magnetic susceptibility, magnetization data and heat capacity measurements support evidence of predominant ferromagnetic correlations, leading to a <italic>s</italic> = 22 spin ground state for the [Mn<sup>III</sup><sub>6</sub>Mn<sup>II</sup><sub>4</sub>] supertetrahedra, which are pair-linked by a weak antiferromagnetic coupling. The properties are discussed in the context of the magnetocaloric effect and the potential application of this compound in cryogenic refrigeration.</p>