While homolytic bond scission is prevailing in polymeric compounds, mechanophores can exhibit new chemistry, which is only accessible by mechanical force. One well-known example is the mechanically induced electrocyclic ring opening reaction of benzocyclobutene. ). No radical generation is observed along the MPES, indicating that only the electrocyclic mechanism is accessible in these compounds. This is in line with experiments and previous computational studies on this system. Compounds 8 and 9 are mechanophores, which are believed to undergo mainly heterocyclic ring opening. This is especially interesting, since molecular bond scission in all of our polymer systems as discussed above showed either homolytic scission or mechanoreactions. Our CoGEF calculations confirm the heterolytic bond scission for molecule 8 for all functionals. No radical pathway was observed, although the radical pathway, besides a concerted pathway, which directly produces a n-herterocyclic carbene, was shown to be accessible experimentally. With BP86-D3 we observe that a proton can be easily abstracted by the anionic scission partner, which is corroborated by experiments. It is, however, not the proton located at the heterocycle that is abstracted. Instead, a methyl proton is abstracted followed by ring closure as depicted in Figure . More importantly, our CoGEF calculations do not confirm the heterolytic bond scission for mechanophore 9 at all. Instead, a plethora of different homolytic pathways was observed (Scheme 1), all of which support the idea of a radical unzipping pathway. This is not in line with previous reports either experimentally, or computationally. For this reason, we also conducted CoGEF calculations with restricted Kohn Sham (RKS) theory, however, the unrestricted pathway is thermodynamically favorable in all cases (Figure ). The observed maximum Forces are identical between UKS and RKS procedures (Table and Table ). It is noteworthy that the presented calculations were conducted on an all-cis isomer of 9, similar to previous work. We performed also test calculations on an all-trans isomer, which indicate that in this case also a homolytic scission pathway is prevailing (SI), however, the scission products again differ from the ones delineated in Scheme 1.