Watching Hydrogens Migrate: Step by Step from [ReI(η6-C6H6)2]+ to [ReIII(η3-C6H9)(η6-C6H6)(NCCH3)2]2+

Arene substitution reactions in [M(eta(6)-arene)(2)](0/2+ )are well documented for Groups 6 and 8 but are essentially unknown for the manganese triad. Aiming to replace benzene in [Re-I(eta(6)-C6H6)(2)](+), we altered the hapticity of one coordinated benzene, which we found to be tunable stepwise from an eta(6) to an eta(3)-ally1 coordination mode. Reduction of [Re-I(eta(6)-C6H6)(2)](+) with hydrides gives [Re-I(eta(5)-C6H7)(eta(6)-C6H6)]. Subsequent addition of acid yields [(ReH)-H-III(eta(5)-C6H7)(eta(6)-C6H6)](+), which converts to [Re-I(eta(4)-C6H8)(eta(6)-C6H6)NCCH3](+) acetonitrile. Further protonation gives the title complex [Re-III(eta(3)-C6H9)(eta(6)-C6H6)(NCCH3)(2)](+) by a rhenium-mediated, intramolecular hydride shift. Herein, we present a full mechanistic elucidation of these transformations based on NMR studies, isolation of reaction intermediates, and their full characterizations. The structural feature {Re-III(eta(6)-C6H6)} is unprecedented. Direct arene exchange from [Re-I(eta(6)-C6H6)(2)](+) to [Re-I(eta(6)-arene)(eta(6)-C6H6)](+) was found only under strongly acidic conditions in neat arene. The analogous chemistry of the different. Treatment of [Tc-I(eta(5)-C6H7)(eta(6)-C6H6)] with acid in acetonitrile [Tc-II(NCCH3)(6)](2+).

Automated summary

In this study, the arene substitution reactions of manganese were investigated and benzene substitution was achieved by altering the hapticity of coordinated benzene. Mechanistic elucidation of these reactions was carried out through NMR studies, isolation of reaction intermediates, and comprehensive characterizations. The results highlight the significant reactivity and mechanistic insights of these reactions.