Institut für Anorganische Chemie und Kristallographie, Universität Bremen, Leobener Straße 7, 28359, Bremen, Germany.
Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195, Berlin, Germany.
Chemistry. 2019 Nov 22;25(65):14758-14761. doi: 10.1002/chem.201902520. Epub 2019 Oct 24.
Fluoride abstraction from bis-m-terphenylelement fluorides (2,6-Mes C H ) EF (E=P, As) generated the highly reactive phosphenium ion [(2,6-Mes C H ) P] and the arsenium ion [(2,6-Mes C H ) As] , which immediately underwent intramolecular electrophilic substitution and formation of an 1,2,4-trimethyl-6-mesityl-5-m-terphenyl-benzo[b]phospholium ion and an 1,2,4-trimethyl-6-mesityl-5-m-terphenyl-benzo[b]arsolium ion, respectively. The formation of the latter involved a methyl group migration from the ortho-position of a flanking mesityl group to the meta-position. This reactivity of [(2,6-Mes C H ) E] (E=P, As) is in sharp contrast to the related stibenium ion [(2,6-Mes C H ) Sb] and bismuthenium ion [(2,6-Mes C H ) Bi] , which have been recently isolated and fully characterized (Angew. Chem. Int. Ed. 2018, 57, 10080-10084). On the basis of DFT calculations, a mechanism for the rearrangement of the phosphenium and arsenium ions into the phospholium and arsolium ions is proposed, which is not feasible for the stibenium and bismuthenium ions.
双-间-三联苯氟化物（2,6-Mes C H ）EF（E=P、As）中的氟原子被夺走，生成了高活性的膦翁离子[(2,6-Mes C H ) P]和砷翁离子[(2,6-Mes C H ) As]，它们立即进行分子内亲电取代反应，分别形成 1,2,4-三甲基-6-均三甲苯基-5-间三联苯苯并[b]磷翁离子和 1,2,4-三甲基-6-均三甲苯基-5-间三联苯苯并[b]砷翁离子。后者的形成涉及到一个甲基从邻位均三甲苯基基团迁移到间位。[(2,6-Mes C H ) E]（E=P、As）的这种反应性与最近分离并充分表征的相关联苯翁离子[(2,6-Mes C H ) Sb]和铋翁离子[(2,6-Mes C H ) Bi]形成鲜明对比（Angew. Chem. Int. Ed. 2018, 57, 10080-10084）。基于 DFT 计算，提出了膦翁离子和砷翁离子重排为磷翁离子和砷翁离子的反应机理，该机理不适用于联苯翁离子和铋翁离子。
