A Uranium(IV) Triamide Species with Brønsted Basic Ligand Character: Metal–Ligand Cooperativity in the f Block

详细信息    查看全文

• 作者：John J. Kiernicki ; Selena L. Staun ; Matthias Zeller ; Suzanne C. Bart
• 刊名：Organometallics
• 出版年：2017
• 出版时间：February 13, 2017
• 年：2017
• 卷：36
• 期：3
• 页码：665-672
• 全文大小：489K
• ISSN：1520-6041

文摘

Deprotonation of the tridentate triamine ligand H₃N₃^Mes ((2,4,6-Me₃C₆H₂N(H)CH₂CH₂)₂NH) with 2 equiv of KCH₂Ph followed by treatment with 1 equiv of UCl₄ afforded the diamidoamine uranium complex (THF)₂UCl₂(HN₃^Mes) (1-THF). This species was further derivatized with either O═PPh₃ or KCp* to generate (Ph₃PO)UCl₂(HN₃^Mes) (1-OPPh₃) or Cp*UCl(HN₃^Mes) (2-Cl), respectively. Deprotonation of 2-Cl with ⁿBuLi furnished the uranium(IV) triamido compound Cp*U(N₃^Mes-LiCl(THF)₂) (3-LiCl), which is stabilized by the presence of LiCl. 3-LiCl reacts readily with alcohols and thiols, including HOPh, HSPh, and HO^tBu, to furnish the respective products Cp*U(OPh)(HN₃^Mes) (2-OPh), Cp*U(SPh)(HN₃^Mes) (2-SPh), and Cp*U(O^tBu)(HN₃^Mes) (2-O^tBu), which show cooperative addition of the H–E (E = O, S) bond across the U–N bond, serving to regenerate the diamidoamine ligand. Similar cooperative addition was noted for 3-LiCl with benzophenone, furnishing Cp*U(N₃^Mes-OCPh₂) (3-OCPh₂), which features new U–O and N–C bonds. The Brønsted basicity of the central nitrogen of 3-LiCl was illustrated by addition of PhOAc, which favored α-carbon deprotonation over nucleophilic attack at the carbonyl. All species were subject to a complete spectroscopic and crystallographic analysis, confirming that the reactivity of 3-LiCl in fact involves cooperation from the triamido ligand and uranium center.