Structural and Density Functional Studies of Uranium(III) and Lanthanum(III) Complexes with a Neutral Tripodal N-Donor Ligand Suggesting the Presence of a U−N Back-Bonding Interaction
作者:Marinella Mazzanti、Raphaël Wietzke、Jacques Pécaut、Jean-Marc Latour、Pascale Maldivi、Michael Remy
DOI:10.1021/ic010839v
日期:2002.5.1
U-N bonding. The selectivity of the tpza ligand toward U(III) complexation (with respect to that of La(III)) in the presence of sigma-donor-only ligands has been quantified by the value of K(U(tpza))/K(La(tpza)) measured to be 3.3 +/- 0.5. The analysis of the metal-N-donor ligand bonding was carried out by a quasi-relativistic density functional theory study on small model compounds, of formula I(3)M-L
三[(2-吡嗪基)甲基]胺(tpza)的两种三碘化物八配位铀(III)配合物的晶体结构,其区别仅在于占据第八个配位点(thf或MeCN)的配体及其镧(III) )类似物已经确定。在乙腈加合物中,U(III)和La(III)的MN(吡嗪)距离非常相似,而UN(乙腈)的距离比La-N(乙腈)距离短0.05A。在[M(tpza)I(3)(thf)]络合物中,单齿乙腈配体(一种弱的pi受体配体)被thf分子(仅一个σ供体)代替,距离UN的平均值(吡嗪)比La-N(吡嗪)距离的平均值短0.05A。由于我们正在比较离子半径非常相似的离子的同构化合物,这些差异表明在U(III)配合物中存在更强的MN相互作用,因此表明对UN键合存在共价贡献。在仅存在σ供体的配体存在下,tpza配体对U(III)络合的选择性(相对于La(III)的选择性)已通过K(U(tpza))/ K( La(tpza))测量为3.3 +/-