Lichtenberg Crispin
Julius-Maximilians-University Würzburg, Institute of Inorganic Chemistry Am Hubland, 97074 Würzburg, Germany.
Chem Commun (Camb). 2021 May 6;57(37):4483-4495. doi: 10.1039/d1cc01284c.
Cationic bismuth(iii) species [BiR2]+ with weakly coordinating counteranions feature two monoanionic ligands R (such as aryls, amides, alcoholates or halides), a vacant bismuth-centred p-orbital, and an occupied bismuth-centred s-orbital. The vacant orbital is available for intra- and intermolecular σ- and π-type bonding interactions and plays a crucial role in redox chemistry. The occupied s-orbital may also show minor contributions to dative bonding and is essential when addressing reversible Bi(iii)/Bi(v) redox shuttling. Variation of the anionic ligands R, the weakly coordinating counter anions, and potential neutral ligands L allows precise fine-tuning of the coordination chemistry, Lewis acidity, redox-properties, and reactivity towards nucleophiles. This contribution summarises the fundamental properties of well-defined molecular cationic bismuth compounds and highlights recent advancements in the understanding of their Lewis acidity, in their utilisation for challenging stoichometric reactions (such as CH activation and small molecule activation), and in catalytic applications (such as Lewis acid catalysis, radical polymerisation, and Bi(iii)/Bi(v) redox catalysis).
具有弱配位抗衡阴离子的阳离子铋（III）物种[BiR2]+具有两个单阴离子配体R（如芳基、酰胺、醇盐或卤化物）、一个以铋为中心的空p轨道和一个以铋为中心的被占据s轨道。该空轨道可用于分子内和分子间的σ型和π型键合相互作用，并且在氧化还原化学中起关键作用。被占据的s轨道对给予键也可能有较小贡献，并且在研究可逆的Bi（III）/Bi（V）氧化还原穿梭时至关重要。阴离子配体R、弱配位抗衡阴离子以及潜在的中性配体L的变化允许对配位化学、路易斯酸性、氧化还原性质以及对亲核试剂的反应性进行精确微调。本论文总结了结构明确的分子阳离子铋化合物的基本性质，并突出了在理解其路易斯酸性、将其用于具有挑战性的化学计量反应（如C-H活化和小分子活化）以及催化应用（如路易斯酸催化、自由基聚合和Bi（III）/Bi（V）氧化还原催化）方面的最新进展。
