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Probing Magnetic‐Exchange Coupling in Supramolecular Squares Based on Reducible Tetrazine‐Derived Ligands
Author(s) -
Lemes Maykon A.,
Stein Hilarie N.,
Gabidullin Bulat,
Robeyns Koen,
Clérac Rodolphe,
Murugesu Muralee
Publication year - 2018
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.201800126
Subject(s) - tetrazine , delocalized electron , chemistry , supramolecular chemistry , counterion , coupling (piping) , computational chemistry , crystallography , crystal structure , materials science , ion , organic chemistry , metallurgy
Reducible 3,6‐bis(3,5‐dimethyl‐pyrazolyl)1,2,4,5‐tetrazine was employed to isolate supramolecular air‐stable [Co 4 ] and [Zn 4 ] squares, which were achieved via careful selection of counterions rather than the use of reducing agents. Magnetic susceptibility studies revealed a strong radical‐Co II exchange coupling ( J rad‐Co / hc =−118 cm −1 , −2 J formalism) with a spin ground state of S T =4, whereas the unreduced analogue revealed negligible coupling between the Co centers ( J Co‐Co / hc =−0.64 cm −1 ). Radical–radical coupling was also probed in the [Zn 4 ] congener, which led to J rad‐rad / hc =−15.9(5) cm −1 . These results highlight the versatile air‐stable coordination chemistry of tetrazine and the importance of exploiting easily reducible delocalized radical to promote strong exchange coupling between spin carriers.