TY - JOUR

T1 - Fluoride-bridged {GdIII3MIII2} (M=Cr, Fe, Ga) molecular magnetic refrigerants

AU - Pedersen, Kasper Steen

AU - Lorusso, Giulia

AU - Morales, Juan José

AU - Weyhermüller, Thomas

AU - Piligkos, Stergios

AU - Singh, Saurabh Kumar

AU - Larsen, Dennis

AU - Schau-Magnussen, Magnus

AU - Rajaraman, Gopalan

AU - Evangelisti, Marco

AU - Bendix, Jesper

PY - 2014

Y1 - 2014

N2 - The reaction of fac-[MIIIF3(Me3tacn)] ×x H2O with Gd(NO3)3×5H 2O affords a series of fluoride-bridged, trigonal bipyramidal {GdIII3MIII2} (M=Cr (1), Fe (2), Ga (3)) complexes without signs of concomitant GdF3 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. Molecular coolers: Even labile fluoride complexes (see picture; Gd purple, Cr/Fe/Ga orange, F green, O red) are useful precursors for polynuclear, fluoride-bridged 3d-4f systems. Molecular geometry enforces weak exchange interactions, which is rationalized computationally. This, in conjunction with a lightweight auxiliary ligand sphere, gives rise to extremely large magnetic entropy changes.

AB - The reaction of fac-[MIIIF3(Me3tacn)] ×x H2O with Gd(NO3)3×5H 2O affords a series of fluoride-bridged, trigonal bipyramidal {GdIII3MIII2} (M=Cr (1), Fe (2), Ga (3)) complexes without signs of concomitant GdF3 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. Molecular coolers: Even labile fluoride complexes (see picture; Gd purple, Cr/Fe/Ga orange, F green, O red) are useful precursors for polynuclear, fluoride-bridged 3d-4f systems. Molecular geometry enforces weak exchange interactions, which is rationalized computationally. This, in conjunction with a lightweight auxiliary ligand sphere, gives rise to extremely large magnetic entropy changes.

KW - density functional calculations

KW - fluoride ligands

KW - lanthanides

KW - magnetic properties

KW - magnetic refrigeration

U2 - 10.1002/anie.201308240

DO - 10.1002/anie.201308240

M3 - Journal article

AN - SCOPUS:84894435310

VL - 53

SP - 2394

EP - 2397

JO - Angewandte Chemie International Edition

JF - Angewandte Chemie International Edition

SN - 1433-7851

IS - 9

ER -