title: Electronic Structure and Magnetic Properties of Dioxo-Bridged Diuranium Complexes with Diamond-Core Structural Motifs: A Relativistic DFT Study.
abstract: Electronic structures and magnetic properties of the binuclear bis(μ-oxo) U(IV)/U(IV) K2[{(((nP,Me)ArO)3tacn)U(IV)}2(μ-O)2] and U(V)/U(V) [{(((nP,Me)ArO)3tacn)U(V)}2(μ-O)2] (tacn = triazacyclononane, nP = neopentyl) complexes, exhibiting [U(μ-O)2U] diamond-core structural motifs, have been investigated computationally using scalar relativistic Density Functional Theory (DFT) combined with the Broken Symmetry (BS) approach for their magnetic properties. Using the B3LYP hybrid functional, the BS ground state of the pentavalent [U(V)(μ-O)2U(V)] 5f(1)-5f(1) complex has been found of lower energy than the high spin (HS) triplet state, thus confirming the antiferromagnetic character in agreement with experimental magnetic susceptibility measurements. The nonmagnetic character observed for the tetravalent K2[U(IV)(μ-O)2U(IV)] 5f(2)-5f(2) species is also predicted by our DFT calculations, which led practically to the same energy for the HS and BS states. As reported for related dioxo diuranium(V) systems, superexchange is likely to be responsible for the antiferromagnetic coupling through the π-network orbital pathway within the (μ-O)2 bridge, the dissymmetrical structure of the U2O2 core playing a determining role. In the case of the U(IV) species, our computations indicate that the K(+) counterions are likely to play a role for the observed magnetic property. Finally, the MO analysis, in conjunction with NPA and QTAIM analyses, clarify the electronic structures of the studied complexes. In particular, the fact that the experimentally attempted chemical oxidation of the U(V) species does not lead straightforwardly to binuclear complexes U(VI) is clarified by the MO analysis.
authors.affiliation: Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1 , Campus de Beaulieu, F-35042 Cedex Rennes, France.|URCHEMS, Département de Chimie, Université des Frères Mentouri , 25017 Constantine, Algeria.|Université Ziane Achour de Djelfa , 17000 Djelfa, Algeria.
authors.forename: Billel
authors.initials: B
authors.lastname: Teyar
authors.affiliation: URCHEMS, Département de Chimie, Université des Frères Mentouri , 25017 Constantine, Algeria.
authors.forename: Lotfi
authors.initials: L
authors.lastname: Belkhiri
authors.affiliation: Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1 , Campus de Beaulieu, F-35042 Cedex Rennes, France.
authors.forename: Karine
authors.initials: K
authors.lastname: Costuas
authors.affiliation: Institut des Sciences Chimiques de Rennes, UMR 6226 CNRS-Université de Rennes 1 , Campus de Beaulieu, F-35042 Cedex Rennes, France.
authors.forename: Abdou
authors.initials: A
authors.lastname: Boucekkine
authors.affiliation: Department of Chemistry & Pharmacy, Friedrich-Alexander University of Erlangen - Nürnberg (FAU) , Egerlandstrasse 1, D-91058 Erlangen, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Meyer