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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Access to novel fluorovinylidene ligands via exploitation of outer-sphere electrophilic fluorination: new insights into C-F bond formation and activation
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Access to novel fluorovinylidene ligands via exploitation of outer-sphere electrophilic fluorination: new insights into C-F bond formation and activation

机译：通过利用外球亲电氟化获得新型氟亚乙烯基配体：对C-F键形成和活化的新见解

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摘要

Metal vinylidene complexes are widely encountered, or postulated, as intermediates in a range of important metal-mediated transformations of alkynes. However, fluorovinylidene complexes have rarely been described and their reactivity is largely unexplored. By making use of the novel outer-sphere electrophilic fluorination (OSEF) strategy we have developed a rapid, robust and convenient method for the preparation of fluorovinylidene and trifluoromethylvinylidene ruthenium complexes from non-fluorinated alkynes. Spectroscopic investigations (NMR and UV/Vis), coupled with TD-DFT studies, show that fluorine incorporation results in significant changes to the electronic structure of the vinylidene ligand. The reactivity of fluorovinylidene complexes shows many similarities to non-fluorinated analogues, but also some interesting differences, including a propensity to undergo unexpected C-F bond cleavage reactions. Heating fluorovinylidene complex [Ru(eta(5)-C5H5)(PPh3)(2)(C=C{F}R)][BF4] led to C-H activation of a PPh3 ligand to form an orthometallated fluorovinylphosphonium ligand. Reaction with pyridine led to nucleophilic attack at the metal-bound carbon atom of the vinylidene to form a vinyl pyridinium species, which undergoes both C-H and C-F activation to give a novel pyridylidene complex. Addition of water, in the presence of chloride, leads to anti-Markovnikov hydration of a fluorovinylidene complex to form an alpha-fluoroaldehyde, which slowly rearranges to its acyl fluoride isomer. Therefore, fluorovinylidenes ligands may be viewed as synthetic equivalents of 1-fluoroalkynes providing access to reactivity not possible by other routes.
机译：金属亚乙烯基络合物作为炔在一系列重要的金属介导转化中的中间体而被广泛使用或假定。然而，氟亚乙烯基配合物很少被描述，并且它们的反应性在很大程度上尚待探索。通过使用新颖的外球亲电氟化（OSEF）策略，我们开发了一种快速，耐用和方便的方法，用于从非氟化炔烃制备氟亚乙烯基和三氟甲基亚乙烯基钌配合物。光谱研究（NMR和UV / Vis）以及TD-DFT研究表明，氟的引入导致亚乙烯基配体的电子结构发生重大变化。氟亚乙烯基配合物的反应性与非氟化类似物有很多相似之处，但也有一些有趣的区别，包括容易发生意想不到的C-F键断裂反应。加热氟亚乙烯基配合物[Ru（eta（5）-C5H5）（PPh3）（2）（C = C {F} R）] [BF4]导致PPh3配体的C-H活化，从而形成正金属化的氟乙烯基ligand配体。与吡啶的反应导致在亚乙烯基的金属键合的碳原子上发生亲核攻击，形成乙烯基吡啶鎓物质，该乙烯基吡啶鎓化合物同时经历C-H和C-F活化，从而得到新型的吡啶亚基络合物。在氯化物的存在下添加水会导致氟亚乙烯基配合物的抗马尔科夫尼科夫水合反应，形成α-氟醛，然后缓慢重排为其酰基氟异构体。因此，氟亚乙烯基配体可被视为1-氟炔烃的合成等同物，从而提供了其他途径无法实现的反应性。

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