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Reactions of aluminium(I) with transition metal carbonyls: scope, mechanism and selectivity of CO homologation
Chemical Science ( IF 7.6 ) Pub Date : 2021-10-25 , DOI: 10.1039/d1sc04940b
Richard Y Kong 1 , Maria Batuecas 1 , Mark R Crimmin 1
Affiliation  

Over the past few decades, numerous model systems have been discovered that create carbon–carbon bonds from CO. These reactions are of potential relevance to the Fischer–Tropsch process, a technology that converts syngas (H2/CO) into mixtures of hydrocarbons. In this paper, a homogeneous model system that constructs carbon chains from CO is reported. The system exploits the cooperative effect of a transition metal complex and main group reductant. An entire reaction sequence from C1 → C2 → C3 → C4 has been synthetically verified. The scope of reactivity is broad and includes a variety of transition metals (M = Cr, Mo, W, Mn, Re, Co), including those found in industrial heterogeneous Fischer–Tropsch catalysts. Variation of the transition metal fragment impacts the relative rate of the steps of chain growth, allowing isolation and structural characterisation of a rare C2 intermediate. The selectivity of carbon chain growth is also impacted by this variable; two distinct isomers of the C3 carbon chain were observed to form in different ratios with different transition metal reagents. Based on a combination of experiments (isotope labelling studies, study of intermediates) and calculations (DFT, NBO, ETS-NOCV) we propose a complete mechanism for chain growth that involves defined reactivity at both transition metal and main group centres.

中文翻译:

铝 (I) 与过渡金属羰基化合物的反应:CO 同系化的范围、机制和选择性

在过去的几十年里,已经发现了许多由 CO 产生碳-碳键的模型系统。这些反应与 Fischer-Tropsch 过程具有潜在的相关性,Fischer-Tropsch 过程是一种将合成气 (H 2 /CO) 转化为碳氢化合物混合物的技术。在本文中,报告了一种从 CO 构建碳链的均质模型系统。该系统利用了过渡金属配合物和主族还原剂的协同作用。从 C 1 → C 2 → C 3 → C 4的整个反应序列已经综合验证。反应性范围很广,包括各种过渡金属(M = Cr、Mo、W、Mn、Re、Co),包括在工业非均相费托催化剂中发现的那些。过渡金属片段的变化会影响链增长步骤的相对速率,从而实现稀有 C 2中间体的分离和结构表征。碳链增长的选择性也受这个变量的影响;C 3 的两种不同异构体观察到碳链与不同的过渡金属试剂以不同的比例形成。基于实验(同位素标记研究、中间体研究)和计算(DFT、NBO、ETS-NOCV)的组合,我们提出了一个完整的链增长机制,包括在过渡金属和主族中心确定的反应性。
更新日期:2021-11-03
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