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

作者：Antunes Maria A; Coutinho Joana T; Santos Isabel C; Marcalo Joaquim; Almeida Manuel; Baldovi Jose J; Pereira Laura C J^*; Gaita Arino Alejandro; Coronado Eugenio

来源：Chemistry - A European Journal, 2015, 21(49): 17817-17826.

DOI：10.1002/chem.201503133

• azo compounds
• magnetic properties
• N ligands
• radicals
• uranium

A tetravalent uranium compound with a radical azobenzene ligand, namely, [{(SiMe2NPh)(3)-tacn}U-IV(eta(2)-N2Ph2 center dot)] (2), was obtained by one-electron reduction of azobenzene by the trivalent uranium compound [U-III{(SiMe2NPh)(3)-tacn}] (1). Compound 2 was characterized by single-crystal X-ray diffraction and H-1 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.

• 出版日期2015-12-1