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A Mononuclear Uranium(IV) Single‐Molecule Magnet with an Azobenzene Radical Ligand
Author(s) -
Antunes Maria A.,
Coutinho Joana T.,
Santos Isabel C.,
Marçalo Joaquim,
Almeida Manuel,
Baldoví José J.,
Pereira Laura C. J.,
GaitaAriño Alejandro,
Coronado Eugenio
Publication year - 2015
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.201503133
Subject(s) - azobenzene , chemistry , magnetization , uranium , single crystal , crystallography , lanthanide , relaxation (psychology) , molecule , ligand (biochemistry) , ion , materials science , organic chemistry , social psychology , psychology , biochemistry , physics , receptor , quantum mechanics , magnetic field , metallurgy
A tetravalent uranium compound with a radical azobenzene ligand, namely, [{(SiMe 2 NPh) 3 ‐tacn}U IV (η 2 ‐N 2 Ph 2 . )] ( 2 ), was obtained by one‐electron reduction of azobenzene by the trivalent uranium compound [U III {(SiMe 2 NPh) 3 ‐tacn}] ( 1 ). Compound 2 was characterized by single‐crystal X‐ray diffraction and 1 H NMR, IR, and UV/Vis/NIR spectroscopy. The magnetic properties of 2 and precursor 1 were studied by static magnetization and ac susceptibility measurements, which for the former revealed single‐molecule magnet behaviour for the first time in a mononuclear U IV compound, whereas trivalent uranium compound 1 does not exhibit slow relaxation of the magnetization at low temperatures. A first approximation to the magnetic behaviour of these compounds was attempted by combining an effective electrostatic model with a phenomenological approach using the full single‐ion Hamiltonian.