Sievers Robin, Kub Nico G, Streit Tim-Niclas, Rupf Susanne M, Malischewski Moritz
Institute of Chemistry and Biochemistry - Inorganic Chemistry, Freie Universität Berlin, Fabeckstr. 34/36, 14195, Berlin, Germany.
Chemistry. 2025 May 19;31(28):e202500743. doi: 10.1002/chem.202500743. Epub 2025 Apr 17.
The air- and water-stable perfluorinated Cp* [C(CF)] is presented as a candidate for the vastly underexplored group of weakly coordinating carbanions (WCCAs). Its extreme electron deficiency, combined with the stabilization of the negative charge within an aromatic system, results in a low basicity, yielding a very weak coordination ability. As Cp anions usually possess a strongly pronounced carbanionic character, the perfluorinated Cp* resembles an extraordinary exception for both the WCA and Cp chemistry. However, the coordination ability remains ambivalent due to the substitution lability of many of its complexes, allowing for the formation of unique ligand-WCA switches. Due to the low reactivity, there is a need for new transfer reagents containing the perfluorinated Cp* in combination with reactive cations. Thus, we report the synthesis and complete characterization of [C(CF)] salts with hydride-accepting [(CH)C], valuable Ag(I) reagents, oxidizing [Fe(CH)] or [N(p-CHBr)] and Brønsted acidic [H(m,m-NCHF)]. Notably, these unprecedented ion pairs are exclusively accessible and stabilized by the low coordination affinity and pronounced oxidative resistance of the perfluorinated Cp*.
空气和水稳定的全氟环戊二烯基[C(CF)]被提出作为研究极少的弱配位碳负离子（WCCAs）基团的候选物。其极端的电子缺乏，与芳香体系内负电荷的稳定相结合，导致碱性较低，配位能力非常弱。由于环戊二烯基阴离子通常具有强烈的碳负离子特征，全氟环戊二烯基对于WCA化学和环戊二烯基化学而言都是一个非同寻常的例外。然而，由于其许多配合物的取代不稳定性，配位能力仍然存在矛盾，这使得独特的配体-WCA开关得以形成。由于反应活性较低，需要新型的含有全氟环戊二烯基并与活性阳离子结合的转移试剂。因此，我们报道了[C(CF)]盐与氢化物接受体[(CH)C]、有价值的Ag(I)试剂、氧化性的[Fe(CH)]或[N(p-CHBr)]以及布朗斯特酸性的[H(m,m-NCHF)]的合成及完整表征。值得注意的是，这些前所未有的离子对仅通过全氟环戊二烯基的低配位亲和力和显著的抗氧化性得以获得并稳定。
