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Fluoride‐Bridged {Gd III 3 M III 2 } (M=Cr, Fe, Ga) Molecular Magnetic Refrigerants
Author(s) -
Pedersen Kasper S.,
Lorusso Giulia,
Morales Juan José,
Weyhermüller Thomas,
Piligkos Stergios,
Singh Saurabh Kumar,
Larsen Dennis,
SchauMagnussen Magnus,
Rajaraman Gopalan,
Evangelisti Marco,
Bendix Jesper
Publication year - 2014
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201308240
Subject(s) - magnetic refrigeration , ground state , intramolecular force , ferromagnetism , fluoride , crystallography , trigonal bipyramidal molecular geometry , chemistry , excited state , coordination sphere , antiferromagnetism , magnetization , atomic physics , stereochemistry , magnetic field , crystal structure , inorganic chemistry , condensed matter physics , physics , quantum mechanics
Abstract The reaction of fac ‐[M III F 3 (Me 3 tacn)]⋅ x H 2 O with Gd(NO 3 ) 3 ⋅5H 2 O affords a series of fluoride‐bridged, trigonal bipyramidal {Gd III 3 M III 2 } (M=Cr ( 1 ), Fe ( 2 ), Ga ( 3 )) complexes without signs of concomitant GdF 3 formation, thereby demonstrating the applicability even of labile fluoride‐complexes as precursors for 3d–4f systems. Molecular geometry enforces weak exchange interactions, which is rationalized computationally. This, in conjunction with a lightweight ligand sphere, gives rise to large magnetic entropy changes of 38.3 J kg −1 K −1 ( 1 ) and 33.1 J kg −1 K −1 ( 2 ) for the field change 7 T→0 T. Interestingly, the entropy change, and the magnetocaloric effect, are smaller in 2 than in 1 despite the larger spin ground state of the former secured by intramolecular Fe–Gd ferromagnetic interactions. This observation underlines the necessity of controlling not only the ground state but also close‐lying excited states for successful design of molecular refrigerants.