Terminal Mo Carbide and Carbyne Reactivity: H2 Cleavage, B–C Bond Activation, and C–C Coupling,Organometallics

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Terminal Mo Carbide and Carbyne Reactivity: H2 Cleavage, B–C Bond Activation, and C–C Coupling
Organometallics ( IF 2.5 ) Pub Date : 2021-08-12 , DOI: 10.1021/acs.organomet.1c00336
Gwendolyn A. Bailey ₁ , Theodor Agapie ₁

Affiliation

Transition-metal carbides have been posited as intermediates in the upgrading of C₁ feedstocks, including the Fischer–Tropsch synthesis of higher olefins from CO and H₂. Still, molecular examples remain rare, and their reactivity is poorly understood. In a molecular platform supported by a flexible terphenyl diphosphine ligand, the important C–C coupling step was previously demonstrated on the reaction of Mo carbide and carbene species with CO. Methylidyne and methylidene complexes were accessible on sequential treatment of the carbide with sources of H⁺ and H^–, surrogates for heterolyzed H₂. Herein, we demonstrate that the terminal carbide complex is also capable of directly activating H₂, yielding a P–C-bonded ylide complex. The carbide moiety also inserts into the B–C bond of triphenylborane, yielding an unusual example of a borylcarbene with a direct Mo–B contact. C–C coupling from the terminal methylidyne, a potential intermediate formed on heterolytic H₂ cleavage and H⁺ transfer to the carbide, yields a Mo ketenyl complex, thus giving information for the first time on the relative rates of coupling from carbide, carbyne, and carbene species in the same molecular platform.

中文翻译：

末端 Mo 碳化物和 Carbyne 反应性：H2 裂解、B-C 键活化和 C-C 偶联

过渡金属碳化物已被认为是升级 C ₁原料的中间体，包括从 CO 和 H ₂合成高级烯烃的费-托合成。尽管如此，分子例子仍然很少，而且它们的反应性也知之甚少。在一个由灵活的三联苯二膦配体支撑的分子平台中，重要的 C-C 偶联步骤之前在碳化钼和卡宾物种与 CO 的反应中得到了证明。亚甲基和亚甲基配合物可通过使用 H 源连续处理碳化物来获得⁺和 H ^–是异解 H _{2 的}替代物。在此，我们证明末端碳化物复合物也能够直接激活 H ₂，产生 P-C 键合的叶立德复合物。碳化物部分也插入到三苯基硼烷的 B-C 键中，产生了一个不寻常的例子，即与 Mo-B 直接接触的硼基卡宾。来自末端亚甲基的 C-C 偶联，一种潜在的中间体，在异裂 H ₂裂解和 H ⁺转移到碳化物时形成，产生 Mo 烯酮络合物，从而首次提供有关碳化物、碳炔、和卡宾物种在同一分子平台上。

更新日期：2021-08-23

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