Yuvaraj K, Douair Iskander, Paparo Albert, Maron Laurent, Jones Cameron
School of Chemistry , Monash University , P.O. Box 23, Melbourne , VIC 3800 , Australia.
Université de Toulouse et CNRS , INSA, UPS, UMR 5215, LPCNO, 135 Avenue de Rangueil , F-31077 Toulouse , France.
J Am Chem Soc. 2019 Jun 5;141(22):8764-8768. doi: 10.1021/jacs.9b04085. Epub 2019 May 22.
This study details syntheses of unsymmetrical magnesium(I)-adduct complexes, [(Nacnac)(D)Mg-Mg(Nacnac)] (Nacnac = [(ArNCMe)CH]), Ar = xylyl (Xyl), mesityl (Mes), 2,6-diethylphenyl (Dep), or 2,6-diisopropylphenyl (Dip); D = N-heterocyclic carbene or 4-dimethylaminopyridine, DMAP), which X-ray crystallographic studies show to have markedly elongated Mg-Mg bonds. Two of these highly reactive species are shown to reductively trimerize CO to yield rare crystallographically characterized examples of the planar, aromatic deltate dianion, incorporated in the complexes [{(Nacnac)(D)Mg(μ-CO)Mg(Nacnac)}] (D = DMAP or :C{N(Me)C(Me)}). DFT calculations suggest that these complexes form via stepwise two-electron reductions of three CO molecules, resulting in the formation of three C-C bonds within the cyclic deltate unit. This work highlights the utility of activated magnesium(I) adduct complexes as soluble organometallic models for the study of reductive C-C bond-forming events in, for example, the heterogeneously catalyzed Fischer-Tropsch process.
本研究详细介绍了不对称镁（I）加合物配合物[(Nacnac)(D)Mg-Mg(Nacnac)]（Nacnac = [(ArNCMe)CH]，Ar = 二甲苯基（Xyl）、均三甲苯基（Mes）、2,6-二乙苯基（Dep）或2,6-二异丙苯基（Dip）；D = N-杂环卡宾或4-二甲氨基吡啶，DMAP）的合成，X射线晶体学研究表明其Mg-Mg键明显拉长。其中两种高活性物种被证明可将CO还原三聚，生成平面芳香δ二价阴离子的罕见晶体学表征实例，该阴离子包含在配合物[{(Nacnac)(D)Mg(μ-CO)Mg(Nacnac)}]（D = DMAP或:C{N(Me)C(Me)}）中。密度泛函理论计算表明，这些配合物通过三个CO分子的逐步双电子还原形成，导致在环状δ单元内形成三个C-C键。这项工作突出了活化镁（I）加合物配合物作为可溶性有机金属模型在研究例如多相催化费托过程中还原C-C键形成事件方面的实用性。
