von Grotthuss Esther, Prey Sven E, Bolte Michael, Lerner Hans-Wolfram, Wagner Matthias
Institut für Anorganische Chemie, Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt (Main), Germany.
Angew Chem Int Ed Engl. 2018 Dec 10;57(50):16491-16495. doi: 10.1002/anie.201811135. Epub 2018 Nov 12.
Alkali metal salts M [1] (M=Li, Na) of doubly reduced 9,10-dimethyl-9,10-dihydro-9,10-diboraanthracene (1) instantaneously add the C=O bond of CO across their boron centers to furnish formal [4+2]-cycloadducts M [2]. If only 1 equiv of CO is supplied, these products are stable. In the presence of excess CO , however, C-O bond cleavage occurs and an O equivalent is transferred to CO to furnish CO and [CO ] . With M=Li, Li CO precipitates and the neutral 1 is liberated such that it can be reduced again to establish a catalytic cycle. With M=Na, [CO ] remains coordinated to both boron atoms in a bridging mode (Na [4]). A mechanistic scenario is proposed, based on isolated intermediates and model reactions.
双还原的9,10-二甲基-9,10-二氢-9,10-二硼蒽（1）的碱金属盐M [1]（M = Li，Na）会在其硼中心瞬间加成CO的C=O键，生成形式上的[4+2]环加成产物M [2]。如果仅提供1当量的CO，这些产物是稳定的。然而，在过量CO存在下，会发生C-O键断裂，一个O原子转移至CO生成CO和[CO]。当M = Li时，Li₂CO₃沉淀，中性的1被释放出来，从而可以再次被还原以建立催化循环。当M = Na时，[CO]以桥连模式与两个硼原子保持配位（Na [4]）。基于分离出的中间体和模型反应，提出了一种机理。
