Triazole-derived N-heterocyclic carbenes, triazolylidenes (trz) have become an interesting alternative to the ubiquitous Arduengo-type imidazole-derived carbenes, in part because they are stronger donors, and in other parts due to their versatile synthesis through different types of click reactions. While the use of trz ligands has initially focused on their coordination to precious metals for catalytic applications, the recent past has seen a growing interest in their impact on first-row transition metals. Coordination of trz ligands to such 3d metals is more challenging due to the orbital mismatch between the carbene and the 3d metal center, which also affects the stability of such complexes. Here we summarize the strategies that have been employed so far to overcome these challenges and to prepare first-row transition metal complexes containing at least one trz ligand. Both properties and reactivities of these trz complexes are comprehensively compiled, with a focus on photophysical properties and, in particular, on the application of these complexes in homogeneous catalysis. The diversity of catalytic transformations entailed with these trz 3d metal complexes as well as the record-high performance in some of the reactions underpins the benefits imparted by trz ligands.

中文翻译：

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带有1,2,3-三唑亚基配体的第一排过渡金属配合物在催化及其他领域的应用

三唑衍生的 N-杂环卡宾、三唑基 (trz) 已成为普遍存在的 Arduengo 型咪唑衍生卡宾的有趣替代品，部分原因是它们是更强的供体，而其他部分则由于它们通过不同类型的点击合成的多功能性反应。虽然 trz 配体的使用最初集中在其与贵金属的配位以用于催化应用，但最近人们对其对第一行过渡金属的影响越来越感兴趣。由于卡宾和 3d 金属中心之间的轨道不匹配，trz 配体与此类 3d 金属的配位更具挑战性，这也影响了此类配合物的稳定性。在这里，我们总结了迄今为止为克服这些挑战并制备含有至少一个 trz 配体的第一行过渡金属配合物所采用的策略。这些trz配合物的性质和反应性都得到了全面的整理，重点是光物理性质，特别是这些配合物在均相催化中的应用。这些 trz 3d 金属配合物所带来的催化转化的多样性以及某些反应中创纪录的高性能支撑了 trz 配体所带来的好处。