Synthesis, Characterization, and Stoichiometric U鈥揙 Bond Scission in Uranyl Species Supported by Pyridine(diimine) Ligand Radicals

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• 作者：John J. Kiernicki ; Dennis P. Cladis ; Phillip E. Fanwick ; Matthias Zeller ; Suzanne C. Bart
• 刊名：Journal of the American Chemical Society
• 出版年：2015
• 出版时间：September 2, 2015
• 年：2015
• 卷：137
• 期：34
• 页码：11115-11125
• 全文大小：560K
• ISSN：1520-5126

文摘

Two uranium(VI) uranyl compounds, Cp*UO₂(^MesPDI^Me) (3) and Cp*UO₂(^tBu-^MesPDI^Me) (3-^tBu) (Cp* = 1,2,3,4,5-pentamethylcyclopentadienide; ^MesPDI^Me = 2,6-((Mes)N=CMe)₂C₅H₃N; ^tBu-^MesPDI^Me = 2,6-((Mes)N=CMe)₂-p-C(CH₃)₃C₅H₂N; Mes = 2,4,6-trimethylphenyl), have been synthesized by addition of N-methylmorpholine N-oxide to trianionic pyridine(diimine) uranium(IV) precursors, Cp*U(^MesPDI^Me)(THF) (1), Cp*U(^MesPDI^Me)(HMPA) (1-HMPA), and Cp*U(^tBu-^MesPDI^Me)(THF) (1-^tBu). These uranyl complexes contain singly reduced pyridine(diimine) ligands suggesting formation occurs via cooperative ligand/metal oxidation. Treating 3 or 3-^tBu with stoichiometric equivalents of Me₃SiI results in stepwise oxo silylation to form (Me₃SiO)₂UI₂(^MesPDI^Me) (5) or (Me₃SiO)UI₂(^tBu-^MesPDI^Me) (5-^tBu), respectively. Additional equivalents result in full uranium鈥搊xo bond scission and formation of UI₄(1,4-dioxane)₂ with extrusion of hexamethyldisiloxane. The uranium complexes have been characterized via multinuclear NMR, vibrational, and electronic absorption spectroscopies and, in some cases, X-ray crystallography.