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Rational Improvement of Single‐Molecule Magnets by Enforcing Ferromagnetic Interactions
Author(s) -
Venne JanPhilipp,
Feldscher Bastian,
Walleck Stephan,
Stammler Anja,
Bögge Hartmut,
Schnack Jürgen,
Glaser Thorsten
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201805543
Subject(s) - ferromagnetism , antiferromagnetism , ground state , chemistry , crystallography , spin states , spin (aerodynamics) , ligand (biochemistry) , spin polarization , magnet , excited state , molecule , condensed matter physics , physics , electron , atomic physics , inorganic chemistry , receptor , quantum mechanics , biochemistry , organic chemistry , thermodynamics
The anisotropy barrier of polynuclear single‐molecule magnets is expected to be higher with less tunneling the better stabilized the spin ground state is so that less M S mixing in the ground state and with excited spin states occur. We have realized this experimentally in two structurally related heptanuclear SMMs: the triplesalen‐based [Mn III 6 Cr III ] 3+ and the triplesalalen‐based *[Mn III 6 Cr III ] 3+ . The ligand system triplesalen was developed to enforce ferromagnetic interactions by the spin‐polarization mechanism. However, we found weak antiferromagnetic couplings, that we assigned to an inefficient spin‐polarization by a heteroradialene formation. To prevent this heteroradialene formation, the triplesalalen ligand H 6 talalent Bu2was designed. Here, we present the building block [(talalent Bu2)Mn III 3 ] 3+ and its application for the assembly of [{(talalent Bu2)Mn III 3 } 2 {Cr III (CN) 6 }] 3+ (= *[Mn III 6 Cr III ] 3+ ). Both the trinuclear and heptanuclear complexes are SMMs. The comparison to the related triplesalen complex [(feldt Bu2)Mn III 3 ] 3+ proves the absence of heteroradialene character and the enforcement of ferromagnetic Mn III ‐Mn III interactions in the (talalent Bu2) 6− complexes. This results in an increase of the barrier for spin reversal U eff from 25 K in the triplesalen‐based [Mn III 6 Cr III ] 3+ SMMs to 37 K in the triplesalalen‐based *[Mn III 6 Cr III ] 3+ SMM proving the success of our concept. Based on this study, the next step in the rational improvement of our SMMs is discussed.