Reactivity of 3-Imino-Functionalized Indoles with Rare-Earth-Metal Amides: Unexpected Substituent Effects on C–H Activation Pathways and Assembly of Rare-Earth-Metal Complexes

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• 作者：Xiancui Zhu ; Yang Li ; Yun Wei ; Shaowu Wang ; Shuangliu Zhou ; Lijun Zhang
• 刊名：Organometallics
• 出版年：2016
• 出版时间：June 13, 2016
• 年：2016
• 卷：35
• 期：11
• 页码：1838-1846
• 全文大小：555K
• 年卷期：0
• ISSN：1520-6041

文摘

The reactivities of different 3-imino-functionalized indoles with rare-earth-metal amides [(Me₃Si)₂N]₃RE(μ-Cl)Li(THF)₃ were studied to reveal unexpected substituent effects on C–H bond activation pathways, leading to the formation of unusual rare-earth-metal complexes. The reactions of 3-(tert-butylimino)indole with [(Me₃Si)₂N]₃RE(μ-Cl)Li(THF)₃ produced tetranuclear rare-earth-metal complexes {[η¹:(μ₂-η¹:η¹):η¹-3-(tBuN═CH)C₈H₄N]RE₂(μ₂-Cl)₂(THF)[N(SiMe₃)₂](η¹:η¹-[μ-η⁵:η²-3-(tBuN═CH)C₈H₅N]₂Li)}₂ (RE = Ho (1a), Er (1b)), incorporating a unique indolyl-1,2-dianion through sp² C–H activation bonded with the central metal in η¹:(μ₂-η¹:η¹) mode. The reactions of 3-(phenylimino)indole with [(Me₃Si)₂N]₃RE(μ-Cl)Li(THF)₃ afforded novel binuclear complexes formulated as {3-[PhNCH(CH₂SiMe₂)N(SiMe₃)]C₈H₅NRE(THF)(μ₂-Cl)Li(THF)₂}₂ (RE = Y (2a), Sm (2b), Dy (2c), Yb (2d)) through an unexpected sp³ C–H bond activation with subsequent C–C bond coupling reactions. Treatment of 3-(2-methylphenylimino)indole or 3-(4-methylphenylimino)indole with [(Me₃Si)₂N]₃Yb(μ-Cl)Li(THF)₃ generated the corresponding dinuclear rare-earth-metal amido complexes {3-[(2-MePh)NCH(CH₂SiMe₂)N(SiMe₃)]C₈H₅NYb(THF)(μ₂-Cl)Li(THF)₂}₂ (3) and {3-[(4-MePh)NCH(CH₂SiMe₂)N(SiMe₃)]C₈H₅NYb(THF)(μ₂-Cl)Li(THF)₂}₂ (4), following the same pathway for the formation of complexes 2a–d. Treatment of 3-(4-tert-butylphenylimino)indole with [(Me₃Si)₂N]₃RE(μ-Cl)Li(THF)₃ afforded new hexanuclear rare-earth-metal complexes {3-[(4-^tBu-Ph)NHCH(CH₂SiMe₂)N(SiMe₃)]C₈H₅NREN(SiMe₃)₂}₆ (RE = Dy (5a), Ho (5b), Er (5c)) via sp³ C–H bond activation followed by C–C bond coupling reactions. In contrast, under the same conditions as those for the preparation of 5, the reaction with the corresponding yttrium complex provided the new heterohexayttrium complex {3-[(4-tBu-Ph)NCH(CH₂SiMe₂)N(SiMe₃)]C₈H₅NYN(SiMe₃)₂Li(THF)}₆ (6), having a 4-tBu-anilido moiety. All of these complexes were fully characterized by elemental analysis, spectroscopic methods, and X-ray structure analysis. Plausible pathways for the formation of these different rare-earth-metal complexes were proposed.