Reactivity Profile of a Formally Dicobalt(0) Complex Bound by a Redox-Active Macrocycle

作者：Ariana Z. Spentzos, Shannon A. Ford, Breanna Muldowney, Tianchang Liu, Peng Cui, Michael R. Gau, Patrick J. Carroll, Neil C. Tomson · 发表于：Organometallics · 年份：2024 · DOI：10.1021/acs.organomet.4c00156 · 被引用次数：10 · 研究领域：Metal-Catalyzed Oxygenation Mechanisms、Metal complexes synthesis and properties、Asymmetric Hydrogenation and Catalysis

In this article, we discuss the synthesis, characterization, and reactivity of a neutral dicobalt complex, [Co 2 (PMe 3 ) 2 ] 0, supported by a highly reduced, redox-active macrocyclic ligand. The reducing equivalents stored within the ligand framework proved capable of activating a wide scope of small molecule substrates. The addition of a weak acid, lutidinium triflate, led to the clean formation of a bridging hydride that was found to undergo fluxional geometric changes in solution, while exposure of [Co 2 (PMe 3 ) 2 ] 0 to H 2 resulted in a rare example of net binuclear oxidative addition to give two bridging hydrides. The addition of diphenylacetylene to [Co 2 (PMe 3 ) 2 ] 0 gave an unusual metallacyclobutane configuration for the coordinated alkyne, a geometry that was mirrored by the product obtained on activation of CO 2 by [Co 2 (PMe 3 ) 2 ] 0 . Dinitrogen was not observed to bind to [Co 2 (PMe 3 ) 2 ] 0, but the use of catalytic quantities of [Co 2 (PMe 3 ) 2 ] 0 in mixtures of KC 8 and Me 3 SiCl under 1 atm of N 2 yielded N(SiMe 3 ) 3, which was quantified by conversion into NH 4 Cl. A screen of related dicobalt complexes revealed a dependence on the identity of the precatalyst, with yields of fixed nitrogen ranging up to 50(6)%.