Tetrahalide Complexes of the [U(NR)2]2+ Ion: Synthesis, Theory, and Chlorine K-Edge X-ray Absorption Spectroscopy
详细信息 查看全文
- 作者：Liam P. Spencer ; Ping Yang ; Stefan G. Minasian ; Robert E. Jilek ; Enrique R. Batista ; Kevin S. Boland ; James M. Boncella ; Steven D. Conradson ; David L. Clark ; Trevor W. Hayton ; Stosh A. Kozimor ; Richard L. Martin ; Molly M. MacInnes ; Angela C. Olson ; Brian L. Scott ; David K. Shuh ; Marianne P. Wilkerson
- 刊名：The Journal of the American Chemical Society
- 出版年：2013
- 出版时间：February 13, 2013
- 年：2013
- 卷：135
- 期：6
- 页码：2279-2290
- 全文大小：537K
- 年卷期：v.135,no.6(February 13, 2013)
- ISSN：1520-5126
文摘
Synthetic routes to salts containing uranium bis-imido tetrahalide anions [U(NR)2X4]2鈥?/sup> (X = Cl鈥?/sup>, Br鈥?/sup>) and non-coordinating NEt4+ and PPh4+ countercations are reported. In general, these compounds can be prepared from U(NR)2I2(THF)x (x = 2 and R = tBu, Ph; x = 3 and R = Me) upon addition of excess halide. In addition to providing stable coordination complexes with Cl鈥?/sup>, the [U(NMe)2]2+ cation also reacts with Br鈥?/sup> to form stable [NEt4]2[U(NMe)2Br4] complexes. These materials were used as a platform to compare electronic structure and bonding in [U(NR)2]2+ with [UO2]2+. Specifically, Cl K-edge X-ray absorption spectroscopy (XAS) and both ground-state and time-dependent hybrid density functional theory (DFT and TDDFT) were used to probe U鈥揅l bonding interactions in [PPh4]2[U(NtBu)2Cl4] and [PPh4]2[UO2Cl4]. The DFT and XAS results show the total amount of Cl 3p character mixed with the U 5f orbitals was roughly 7鈥?0% per U鈥揅l bond for both compounds, which shows that moving from oxo to imido has little effect on orbital mixing between the U 5f and equatorial Cl 3p orbitals. The results are presented in the context of recent Cl K-edge XAS and DFT studies on other hexavalent uranium chloride systems with fewer oxo or imido ligands.