Liu Han-Ying, Neale Samuel E, Hill Michael S, Mahon Mary F, McMullin Claire L, Richards Emma
Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.
Organometallics. 2024 Apr 9;43(8):879-888. doi: 10.1021/acs.organomet.4c00076. eCollection 2024 Apr 22.
The bimetallic species, [{SiN}MgNa] [{SiN} = {CHSiMeN(Dipp)}; (Dipp = 2,6--PrCH)], is shown to be a potent reducing agent, able to effect one- or two-electron reduction of either dioxygen, TEMPO, anthracene, benzophenone, or diphenylacetylene. In most cases, the bimetallic reaction products imply that the dissimilar alkaline metal centers react with a level of cooperativity. EPR analysis of the benzophenone-derived reaction and the concurrent isolation of [{SiN}Mg(OCPh)], however, illustrate that treatment with such reducible, but -basic, species can also result in reactivity in which the metals provide independent reaction products. The notable -stereochemistry of the diphenylacetylene reduction product prompted a computational investigation of the PhC≡CPh addition. This analysis invokes a series of elementary steps that necessitate ring-opening via Mg → Na amido group migration of the SiN ligand, providing insight into the previously observed lability of the bidentate dianion and its consequent proclivity toward macrocyclization.
双金属物种[{SiN}MgNa] [{SiN} = {CHSiMeN(Dipp)}; (Dipp = 2,6 - PrCH)]被证明是一种强效还原剂，能够对氧气、TEMPO、蒽、二苯甲酮或二苯乙炔进行单电子或双电子还原。在大多数情况下，双金属反应产物表明不同的碱金属中心以一定程度的协同作用发生反应。然而，对二苯甲酮衍生反应的EPR分析以及[{SiN}Mg(OCPh)]的同时分离表明，用这种可还原但呈碱性的物种处理也可能导致金属提供独立反应产物的反应活性。二苯乙炔还原产物显著的立体化学引发了对PhC≡CPh加成的计算研究。该分析涉及一系列基本步骤，这些步骤需要通过SiN配体的Mg→Na酰胺基迁移来开环，从而深入了解先前观察到的双齿二价阴离子的不稳定性及其随后的大环化倾向。
