Uranium(III) Redox Chemistry Assisted by a Hemilabile Bis(phenolate) Cyclam Ligand: Uranium鈥揘itrogen Multiple Bond Formation Comprising a trans-{RN鈺怳(VI)鈺怤R}2+ Complex

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• 作者：Leonor Maria ; Isabel C. Santos ; V芒nia R. Sousa ; Joaquim Mar莽alo
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：September 21, 2015
• 年：2015
• 卷：54
• 期：18
• 页码：9115-9126
• 全文大小：532K
• ISSN：1520-510X

文摘

A new monoiodide U(III) complex anchored on a hexadentate dianionic 1,4,8,11-tetraazacyclotetradecane-based bis(phenolate) ligand, [U(魏⁶-{(^tBu2ArO)₂Me₂-cyclam})I] (1), was synthesized from the reaction of [UI₃(THF)₄] (THF = tetrahydrofuran) and the respective potassium salt K₂(^tBu2ArO)₂Me₂-cyclam and structurally characterized. Reactivity of 1 toward one-, two-, and four-electron oxidants was studied to explore the reductive chemistry of this new U(III) complex. Complex 1 reacts with one-electron oxidizers, such as iodine and TlBPh₄, to form the seven-coordinate cationic uranium(IV) complexes [U(魏⁶-{(^tBu2ArO)₂Me₂-cyclam})I][X] (X = I (2-I), BPh₄ (2-BPh₄)). The new uranium(III) complex reacts with inorganic azides to yield the pseudohalide uranium(IV) complex [U(魏⁶-{(^tBu2ArO)₂Me₂-cyclam})(N₃)₂] (4) and the nitride-bridged diuranium(IV/IV) complex [(魏⁴-{(^tBu2ArO)₂Me₂-cyclam})(N₃)U(渭-N)U(魏⁵-{(^tBu2ArO)₂Me₂-cyclam})] (5). Two equivalents of [U(魏⁶-{(^tBu2ArO)₂Me₂-cyclam})I] (1) effect the four-electron reduction of 1 equiv of PhN鈺怤Ph to form the bis(imido) complex [U(魏⁴-{(^tBu2ArO)₂Me₂-cyclam})(NPh)₂] (6) and the U(IV) species 2-I. Moreover, the hemilability of the hexadentate ancillary ligand (^tBu2ArO)₂Me₂-cyclam^{2鈥?/sup> allows to perform the reductive cleavage of azobenzene with an unprecedented formation of a trans-bis(imido) complex. The complexes were characterized by NMR spectroscopy, and all the new uranium complexes were structurally authenticated by single-crystal X-ray diffraction.}