Applications of Low-Valent Transition Metalates: Development of a Reactive Noncarbonyl Rhenium(I) Anion
Applications of Low-Valent Transition Metalates: Development of a Reactive Noncarbonyl Rhenium(I) Anion
复制标题
低价过渡金属酸盐的应用：反应性非羰基铼(I)阴离子的开发
DOI：
10.1021/acs.accounts.2c00013
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发表时间：
2022
影响因子：
18.3
通讯作者：
Arnold, John
中科院分区：
文献类型：
--
作者：
Ouellette, Erik T.;Magdalenski, Julian S.;Bergman, Robert G.;Arnold, John
低价过渡金属配合物是一类高活性的有机化学试剂，在有机合成、小分子活化、瞬态物种稳定和M-E键形成等方面有着广泛的应用。这种富电子金属中心的固有反应性使得必须广泛使用强背键配体，特别是羰基，以帮助金属化物试剂的分离和处理，尽管有时以部分掩盖其全部反应性为代价。然而，最近对缺乏典型背键配体的过渡金属配合物的合成探索导致了能够进行各种新颖化学转化的高反应性金属配合物的发现。早中过渡金属化学的一系列合理进展最终导致我们分离出了一个β-二酮亚胺化环戊二烯金属化物，其显示出优异的反应性。我们已经发现这种Re（I）金属配合物能够小分子活化;值得注意的是，该配合物可逆地结合溶液中的双氮，并且可以用于捕获N2用于合成官能化的二氮烯基物质。通过采用等瓣的类似物N2（CO和RNC），我们能够彻底监测的激活机制，并得出结论，金属盐的钠countryside通过一个新的侧上相互作用，在促进二氮激活中发挥着不可或缺的作用。Re（I）金属化物也用于形成各种M-E键，包括一系列不常见的铼-四亚甲基（Si、Ge和Sn）络合物，其显示不同程度的多重键合。这些金属四苯撑的作用是突出14族元素内化学性质的差异。我们的金属化物的效用也适用于金属-金属键的形成，如通过合成的异四金属锌-锌二聚体所示。在该反应中，Re（I）金属配合物作为还原剂和金属配体执行双重作用以稳定瞬时Zn 22+核心片段。最后，金属化物显示出与铀（III）的独特反应性，产生第一过渡金属-锕系元素反夹心键，在这种情况下，三个锕系元素碎片通过其围绕铀中心的Cp部分结合。值得注意的是，在这些努力中，我们证明了金属化物在多个位置处显示出反应性，包括直接在金属中心处、在Cp碳处、通过Cp-夹心模式或通过可逆结合的二氮。小分子活化、还原和/或不稳定物质的稳定化以及非常规M-E/M-M键或异金属络合物的形成。展望未来，我们建议继续发现具有新的或非常规配体的非羰基，富电子过渡金属阴离子，应产生额外的反应性有机金属物种，能够稳定独特的结构图案，并进行新颖和不寻常的化学转化。
ConspectusLow-valent transition metalates─anionic, electronic-rich organometallic complexes─comprise a class of highly reactive chemical reagents that find integral applications in organic synthesis, small-molecule activation, transient species stabilization, and M–E bond formation, among others. The inherent reactivity of such electron-rich metal centers has necessitated the widespread use of strong backbonding ligands, particularly carbonyls, to aid in the isolation and handling of metalate reagents, albeit sometimes at the expense of partially masking their full reactivity. However, recent synthetic explorations into transition-metalate complexes devoid of archetypic back-bonding ligands have led to the discovery of highly reactive metalates capable of performing a variety of novel chemical transformations.Building on our group’s long-standing interest in reactive organometallic species, a series of rational progressions in early-to-middle transition-metal chemistry ultimately led to our isolation of a rhenium(I) β-diketiminate cyclopentadienide metalate that displays exceptional reactivity. We have found this Re(I) metalate to be capable of small-molecule activation; notably, the complex reversibly binds dinitrogen in solution and can be utilized to trap N2for the synthesis of functionalized diazenido species. By employing isolobal analogues to N2(CO and RNC), we were able to thoroughly monitor the mechanism of activation and conclude that the metalate’s sodium counterion plays an integral role in promoting dinitrogen activation through a novel side-on interaction. The Re(I) metalate is also used in forming a variety of M–E bonds, including a series of uncommon rhenium-tetrylene (Si, Ge, and Sn) complexes that display varying degrees of multiple bonding. These metal tetrylenes act to highlight deviations in chemical properties within the group 14 elements. Our metalate’s utility also applies to metal–metal bond formation, as demonstrated through the synthesis of a heterotetrametallic rhenium–zinc dimer. In this reaction, the Re(I) metalate performs a dual role as a reductant and metalloligand to stabilize a transient Zn22+core fragment. Finally, the metalate displays unique reactivity with uranium(III) to yield the first transition metal–actinide inverse-sandwich bonds, in this case with three rhenium fragments bound through their Cp moieties surrounding the uranium center. Notably, throughout these endeavors we demonstrate that the metalate displays reactivity at multiple locations, including directly at the rhenium metal center, at a Cp carbon, through a Cp-sandwich mode, or through reversibly bound dinitrogen.Overall, the rhenium(I) metalate described herein demonstrates utility in diverse applications: small-molecule activation, the stabilization of reduced and/or unstable species, and the formation of unconventional M–E/M–M bonds or heterometallic complexes. Moving forward, we suggest that the continued discovery of noncarbonyl, electron-rich transition-metal anions featuring new or unconventional ligands should produce additional reactive organometallic species capable of stabilizing unique structural motifs and performing novel and unusual chemical transformations.