This Tutorial Review provides an overview of the historic and current development of the organometallic chemistry of cerium in its oxidation state 4+. Among the tetravalent lanthanide ions, only Ce⁴⁺ forms stable coordination compounds (e.g. (NH₄)₂[Ce(NO₃)₆]). Important fields of applications for cerium(IV) compounds include organic synthesis, bioinorganic chemistry, materials science, and industrial catalysis. In sharp contrast, organometallic cerium(IV) compounds are still exceedingly rare. The history of organocerium(IV) compounds is an exciting story of ups and downs. The so-called cerocene (= bis(η⁸-cyclooctatetraenyl) cerium) has been known since 1976. Other early reports e.g. about Cp₄Ce (Cp = η⁵-cyclopentadienyl), were later disproven. However, significant progress in this field has been made in recent years through the use of carefully designed ligands and more sophisticated synthesis protocols. Taking the case of organocerium(IV) chemistry, this Tutorial Review also tries to exemplarily show how difficult synthetic and theoretical problems can eventually be solved through newly designed synthesis strategies (e.g. as accomplished for cyclopentadienyl and carbene derivatives) and a rewarding collaboration between synthetic and theoretical chemists (cf. the cerocene problem).

中文翻译：

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寻找有机铈（IV）化合物的困难

本教程评论概述了氧化态4+的铈有机金属化学的历史和当前发展。在四价镧系离子中，只有Ce ⁴⁺形成稳定的配位化合物（例如（NH ₄）₂ [Ce（NO ₃）₆ ]。铈（IV）化合物的重要应用领域包括有机合成，生物无机化学，材料科学和工业催化。与之形成鲜明对比的是，有机金属铈（IV）化合物仍然极为罕见。有机铈的历史（四））化合物是跌宕起伏的令人振奋的故事。所谓cerocene（=双（η ⁸ -cyclooctatetraenyl）铈）已被公知的自1976年以来的其他早期的报告，例如约的Cp ₄的Ce（CP =η ⁵ -环戊二烯基），后来被证伪。然而，近年来，通过使用精心设计的配体和更复杂的合成方案，该领域取得了重大进展。以有机铈（的情况下IV）化学，此教程审查还试图示范性展示合成和理论问题多么困难最终可以通过新设计的合成策略来解决（如如环戊二烯基和卡宾衍生物所完成的），以及合成化学家和理论化学家之间的有益合作（参见二茂木问题）。