Strongly reducing magnesium(0) complexes
Strongly reducing magnesium(0) complexes
复制标题
DOI：
10.1038/s41586-021-03401-w
复制
发表时间：
2021-04-29
期刊：
影响因子：
64.8
通讯作者：
Harder, S.
中科院分区：
文献类型：
--
作者：
Roesch, B.;Gentner, T. X.;Harder, S.
据报道，含有处于零氧化态的镁的强还原性β-二酮亚胺盐络合物，其中一种具有线性三原子Mg-Mg-Mg核的化合物。处于零氧化态的金属络合物可以被认为是稳定的、但高反应性的单金属原子形式。这种配合物对于更贵重的过渡金属来说是常见的。尽管已知带负电的晚期主族 p 区金属或半金属 (1-6) 的例子很少，但分离处于零氧化态的早期主族 s 区金属 (7-11) 是一个挑战。这与其极低的电负性和强烈的氧化倾向直接相关。在这里，我们展示了零氧化态镁（即镁（0））配合物的例子，这些配合物由超大的单阴离子β-二酮亚胺配体稳定。虽然有机镁化合物的反应性通常由其有机基团的亲核性和 Mg2+ 阳离子的亲电性定义，但本文报道的 Mg-0 配合物具有富电子的镁中心，具有亲核性和强还原性。后一种性质的例子是能够将Na+还原为Na-0。我们还提出了一种具有线性 Mg-3 核心的复合物，其形式上可以描述为 Mg-I-Mg-0-Mg-I 单元。这种多核混合价 Mg-n 簇被讨论为格氏试剂形成早期阶段的短暂中间体。它们非常强的还原能力意味着丰富的反应性和作为专用还原剂的应用。
Strongly reducing beta-diketiminate complexes containing magnesium in its zero oxidation state are reported, among which is a compound with a linear triatomic Mg-Mg-Mg core.A complex of a metal in its zero oxidation state can be considered a stabilized, but highly reactive, form of a single metal atom. Such complexes are common for the more noble transition metals. Although rare examples are known for electronegative late-main-group p-block metals or semimetals(1-6), it is a challenge to isolate early-main-group s-block metals in their zero oxidation state(7-11). This is directly related to their very low electronegativity and strong tendency to oxidize. Here we present examples of zero-oxidation-state magnesium (that is, magnesium(0)) complexes that are stabilized by superbulky, monoanionic, beta-diketiminate ligands. Whereas the reactivity of an organomagnesium compound is typically defined by the nucleophilicity of its organic groups and the electrophilicity of Mg2+ cations, the Mg-0 complexes reported here feature electron-rich Mg centres that are nucleophilic and strongly reducing. The latter property is exemplified by the ability to reduce Na+ to Na-0. We also present a complex with a linear Mg-3 core that formally could be described as a Mg-I-Mg-0-Mg-I unit. Such multinuclear mixed-valence Mg-n clusters are discussed as fleeting intermediates during the early stages of Grignard reagent formation. Their remarkably strong reducing power implies a rich reactivity and application as specialized reducing agents.