Crystal structure diversity in the bis hydrotris-(3,5-dimethylpyrazolyl)borate iodouranium(III) complex: from neutral to cationic forms

The iodouranium(iii) complex with two hydrotris(3,5-dimethylpyrazolyl) borate ligands is shown to adopt three closely related forms in the solid state. In addition to the previously reported structure for [U(TpMe2) 2I], in which one of the pyrazolyl rings coordinates side-on to the U atom, another structure incorporating solvent molecules presents undistorted pyrazol rings, and a third one is the ionic compound [U(TpMe2) 2]I. The implications of this structural diversity for the recently reported single ion magnet behaviour in this complex are discussed, namely on the basis of quantum chemistry calculations. The main effect of the bonding of the iodine atom to uranium is the increase of the size of the first coordination sphere and lowering of the symmetry of the molecule, resulting in a smaller crystal field splitting. © 2013 The Royal Society of Chemistry

Single-ion magnet behaviour in U(Tp(Me2))(2)I

[U(TpMe2)2I] exhibits at low temperatures single molecule magnet (SMM) behaviour comparable to its bipyridine derivative and related single ion U(iii) complexes recently reported as SMMs. The trend of variation of the energy barrier for the magnetic relaxation in these compounds is well reproduced by quantum chemistry calculations. © The Royal Society of Chemistry 2012

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