Reactivity of Organothorium Complexes with TEMPO

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• 作者：Ryan R. Langeslay ; Justin R. Walensky ; Joseph W. Ziller ; William J. Evans
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：August 18, 2014
• 年：2014
• 卷：53
• 期：16
• 页码：8455-8463
• 全文大小：562K
• ISSN：1520-510X

文摘

Reactions of the 2,2,6,6-tetramethylpiperidin-1-oxyl radical (TEMPO) with thorium metallocenes have been examined to investigate both the radical reaction patterns for organothorium complexes and the coordination chemistry of TEMPO with thorium. (畏⁵-C₅Me₅)₂ThMe₂ reacts with 2 equiv of TEMPO to generate 1-methoxy-2,2,6,6-tetramethylpiperidine (Me-TEMPO) and (畏⁵-C₅Me₅)₂ThMe(畏¹-TEMPO), which contains a TEMPO^{鈥?/sup> anion coordinated to thorium through oxygen only. (畏5-C₅Me₅)₂Th(畏1-C₃H₅)(畏3-C₃H₅), synthesized from (畏5-C₅Me₅)₂ThBr₂ and (C₃H₅)MgBr, reacts with 2 equiv of TEMPO to form 1-(2-propen-1-yloxy)-2,2,6,6-tetramethylpiperidine (allyl-TEMPO) and (畏5-C₅Me₅)₂Th(畏1-C₃H₅)(畏1-TEMPO). Although bis(TEMPO) metallocenes were not obtained in these reactions, the methyl group in (畏5-C₅Me₅)₂ThMe(畏1-TEMPO) is reactive with 1 equiv of CuBr to form (畏5-C₅Me₅)₂ThBr(畏1-TEMPO). The bis(TEMPO) metallocene (畏5-C₅Me₅)₂Th(畏1-TEMPO)₂ is accessible in the reaction of [(畏5-C₅Me₅)₂ThH₂]₂ with 4 equiv of TEMPO. In contrast, (畏5-C₅Me₅)₂ThBr₂ reacts with 2 equiv of TEMPO by loss of C₅Me₅ to form (C₅Me₅)₂ and (畏2-TEMPO)₂ThBr₂, in which the TEMPO鈥?/sup> anions bind through oxygen and nitrogen. The bromide ions in (畏2-TEMPO)₂ThBr₂ can be replaced by an additional 2 equiv of TEMPO in the presence of 2 equiv of KC₈ to form the per(TEMPO) complex Th(畏1-TEMPO)₂(畏2-TEMPO)₂. ThBr₄(THF)₄ reacts with TEMPO to form ThBr₄(THF)₂(畏1-TEMPO), which contains an oxygen-bound TEMPO radical. The Th3+ complex (畏5-C₅Me₄H)₃Th is oxidized in the presence of TEMPO, without ligand loss, to afford the Th4+ species (畏5-C₅Me₄H)₃Th(畏1-TEMPO). The reactions show that TEMPO can react with organothorium complexes in several ways including coordination, anion substitution, and cyclopentadienyl replacement.}