Force governs product diversity in the mechanochemical reactivity of triprismane†
Abstract
Unlike conventional modes of activation of reactivity, mechanochemical force provides facile and unique pathways. Extensive studies have been performed on the thermal and photochemical interconversions between benzene and its valence isomers. In this article, we show that mechanochemical pulling along 1,2- positions of triprismane (TP) can precisely control the outcome, namely, benzene (BZ) and/or Dewar benzene (DB), depending upon the strength of external force. Within the force range of 1.5–1.9 nN, DB is formed exclusively, whereas at forces exceeding ≥2.0 nN, BZ becomes the major product. Also, we report that on pulling across 1,4-sites of TP, BZ is produced exclusively when external force ≥1.8 nN. Ab initio steered molecular dynamics (AISMD) simulations on the force modified potential energy surfaces (FMPESs) for 1,2-pulling of TP reveal that DB becomes the minor product beyond external force ≥2.0 nN. The thermodynamically controlled product, BZ, is obtained as the major and sole product for stronger 1,2-pulling and 1,4-pulling respectively. The constrained geometries simulate external force (CoGEF) calculations fail to locate the kinetically trapped intermediate, DB, revealing the prowess of AISMD in revealing unique intermediates and fleetingly stable products in the course of mechanochemical reactions. Also, we demonstrate that the TP → BZ reaction, which demands significant thermal energy, can be induced mechanochemically.