A Mononuclear Uranium(IV) Single-Molecule Magnet with an Azobenzene Radical Ligand

A tetravalent uranium compound with a radical azobenzene ligand, namely, [{(SiMe2NPh)3‐tacn}UIV(η2‐N2Ph2.)] (2), was obtained by one‐electron reduction of azobenzene by the trivalent uranium compound [UIII{(SiMe2NPh)3‐tacn}] (1). Compound 2 was characterized by single‐crystal X‐ray diffraction and 1...

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Bibliographic Details
Published in:Chemistry : a European journal Vol. 21; no. 49; pp. 17817 - 17826
Main Authors: Antunes, Maria A., Coutinho, Joana T., Santos, Isabel C., Marçalo, Joaquim, Almeida, Manuel, Baldoví, José J., Pereira, Laura C. J., Gaita-Ariño, Alejandro, Coronado, Eugenio
Format: Journal Article
Language:English
Published: Weinheim WILEY-VCH Verlag 01.12.2015
WILEY‐VCH Verlag
Wiley Subscription Services, Inc
Subjects:
azo compounds
Chemistry
Diffraction
Electrostatics
Ligands
Low temperature
Magnetic properties
Magnetization
N ligands
Radicals
Reduction
Spectrum analysis
Uranium
Uranium compounds
X-ray diffraction
N ligands
magnetic properties
uranium
radicals
azo compounds
ISSN:0947-6539, 1521-3765, 1521-3765
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Summary:A tetravalent uranium compound with a radical azobenzene ligand, namely, [{(SiMe2NPh)3‐tacn}UIV(η2‐N2Ph2.)] (2), was obtained by one‐electron reduction of azobenzene by the trivalent uranium compound [UIII{(SiMe2NPh)3‐tacn}] (1). Compound 2 was characterized by single‐crystal X‐ray diffraction and 1H 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 UIV 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. Uranium magnet: The mononuclear UIV complex with an azobenzene radical ligand [{(SiMe2NPh)3‐tacn}UIV(η2‐N2Ph2)] exhibits slow relaxation of magnetization with an energy barrier of 17.6 K. This unprecedented behaviour among UIV complexes, due to the interaction of the metal ion with the paramagnetic ligand, was investigated by means of an effective electrostatic model and provides a new strategy to design single‐ion magnets with non‐Kramers ions (see figure).
Bibliography:EU - No. ERC Advanced Grant SPINMOL; No. ERC Consolidator Grant DECRESIM
MINECO
Spanish MINECO - No. MAT2011-22785
FCT - No. UID/Multi/04349/2013
istex:0A5B093C4532CF921877C6D77F198EA62CC8C6AB
FCT (Portugal) - No. PTDC/QEQ-SUP/1413/2012; No. RECI/QEQ-QIN/0189/2012
FCT (Portugal) - No. SFRH/BD/84628/2012; No. SFRH/BPD/74194/2010
ark:/67375/WNG-5J6880VH-7
ArticleID:CHEM201503133
Generalitat Valenciana
ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:0947-6539
1521-3765
1521-3765
DOI:10.1002/chem.201503133