The coupling of CO₂ and ethylene to produce acrylates has been an area of increasing interest in recent years following a number of studies which have empirically improved catalytic turnover. Notably, the incorporation of moderately Brønsted and Lewis basic sodium phenoxide salts, as well as zinc dust, and Lewis acidic lithium salts were found to facilitate acrylate formation in batch catalysis. Despite these advances, there has been limited investigation into the effect of the catalyst ancillary ligand and phenoxide base structure on catalytic performance. Here, a collection of 1,2-bis(dialkylphosphino)benzene and related diphosphine ligands were used to show that the influence of steric environs has a marked effect on turnover. Ancillary diphosphine ligands featuring at least two smaller alkyl substituents are needed for strong activity, while the oft-used benzene annulation of the diphosphine does not appear to be determinant in achieving high turnover values. Additionally, the investigation of a collection of substituted sodium phenoxide bases suggests that a subtle balance of basicity and steric factors must be satisfied to obtain optimal catalytic performance. These trends appear to result from competitive, deleterious nucleophilic reactions between base and CO₂ to produce carbonate and the need to maintain sufficient basicity and access to the metal coordination sphere to drive the endergonic CO₂–ethylene coupling reaction.

中文翻译：

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辅助配体和碱对镍催化的CO ₂和乙烯与丙烯酸酯偶联的影响

CO ₂的耦合近年来，随着大量研究在经验上提高了催化转化率，乙烯和生产丙烯酸酯的领域已成为人们越来越感兴趣的领域。值得注意的是，发现适度的Brønsted和Lewis碱性酚盐钠盐以及锌粉和Lewis酸性锂盐的掺入有助于分批催化中丙烯酸酯的形成。尽管取得了这些进展，但对催化剂辅助配体和酚盐碱结构对催化性能的影响的研究仍有限。在这里，使用了1,2-双（二烷基膦基）苯和相关的二膦配体的集合，表明空间环境的影响对营业额有显着影响。为了增强活性，需要具有至少两个较小的烷基取代基的辅助二膦配体，虽然经常使用的二膦苯环化似乎并不能决定高营业额。另外，对一组取代的苯酚钠碱的研究表明，必须满足碱性和空间因素的微妙平衡，才能获得最佳的催化性能。这些趋势似乎是由于碱和一氧化碳之间发生竞争性，有害的亲核反应所致₂产生碳酸盐，并且需要保持足够的碱度并需要进入金属配位球以驱动碳原子的CO _2-乙烯偶联反应。