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首页> 外文期刊>Chemistry: A European journal >{FeCp}~+-Induced Hexafunctinalization of Hexamethylbenzene with Dendrons for the Direct Synthesis of Redox-Active iron-Centered Metallodendrimers
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{FeCp}~+-Induced Hexafunctinalization of Hexamethylbenzene with Dendrons for the Direct Synthesis of Redox-Active iron-Centered Metallodendrimers

机译：{FeCp}〜+诱导的六甲基苯六甲基苯的十六烷基化反应，以直接合成氧化还原活性的以铁为中心的金属树枝状大分子

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Phenol tri- and nonaallyl dendrons (3 and 7, respectively) were functionalized at the focal position to give the new triallyl dendrons 4 and 6 and the nonaallyl dendrons 11 and 13 that contain a iodoalkyl or a bromobenzyl termini. All these dendrons were used for the {FeCp}~+-induced hexafunctionalization of hexamethylbenzene in [FeCp(#eta#~6-C_6Me_6)][PF_6] (1) under mild conditions in the presence of KOH. These reactions directly yiekded the 18-allyl and 54-allyl dendrimers 9, 10, and 14 with a [FeCp(#eta#~6-arene)]~+ unit located at the dendrimer core. Cyclic voltammetry studies were recorded in THF and DMF with these metallodendrimers and compared with those of anlaogous dendrimers or complexes of smaller size that contain a [FeCp(#eta#~6-arene)]~+ unit at the core. The decreased rate of heterogeneous electron transfer when the dendritic size increases first disclosed by Diederich and Gross is confirmed. The variation of the redox potential of the Fe~(II/I) redox system with increasing dendritic size is negligible even in a solvent of high dielectric constant such as DMF. This trend is attributed to fact that the involved "redox" orbital is buried on the metal center, well protected by the shell of alkyl chains (electron-reservoir nature), unlike in ferrocene. The chemical irreversibility increases in THF as the dendrimer size increases, due tot more facile ligand
机译：在焦点位置将苯酚三烯丙基和九烯丙基树枝状分子（分别为3和7）官能化，以生成新的三烯丙基树枝状分子4和6以及包含碘代烷基或溴苄基末端的九烯丙基树枝状分子11和13。所有这些树枝状分子均在温和条件下在KOH存在下用于{FeCp}〜+诱导的[FeCp（＃eta＃〜6-C_6Me_6）] [PF_6]（1）中六甲基苯的六官能化。这些反应直接用位于树枝状聚合物核心的[FeCp（＃η6〜6-芳烃）] +单元产生18-烯丙基和54-烯丙基树枝状聚合物9、10和14。用这些金属树枝状大分子在THF和DMF中记录了循环伏安法研究，并将其与在核心处含有[FeCp（＃eta＃〜6-芳烃）] +单元的粗枝状大分子或较小尺寸的配合物进行了比较。 Diederich和Gross首先证实了当树枝状晶体尺寸增加时异质电子转移速率降低。即使在高介电常数的溶剂（例如DMF）中，Fe〜（II / I）氧化还原体系的氧化还原电势随树枝状晶尺寸的增加也可以忽略不计。这种趋势归因于以下事实：与二茂铁不同，所涉及的“氧化还原”轨道埋在金属中心，并受到烷基链壳的良好保护（电子-储库性质）。随着树枝状聚合物尺寸的增加，THF中的化学不可逆性增加，这是由于配体更容易

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