The mechanism of C-H functionalization remains unclear when using [Rh 2 (esp) 2 ] as the catalyst as it likely occurs through either a concerted asynchronous nitrenoid insertion or a stepwise C-H abstraction/radical rebound pathway. The computational study by Nörder et al. also identified a singlet transition state from the substrate to the nitrene's nitrogen atom, which could indicate a hydride transfer. In any case of the mechanism, the consensus is that the electrophilic nitrogen atom abstracts either hydrogen or hydride, creating a (partial) positive charge on carbon and a (partial) negative charge on nitrogen. For the azidation reaction , adding TEMPO or BHT, known radical quenchers, inhibited the reaction, suggesting a radical intermediate. However, the detailed mechanism remains unclear, and site selectivity aligns with either hydrogen abstraction (radical formation) or hydride abstraction (carbocation formation). Judging from the QM workflow (MCC: 0.62) as the best-performing method, it can indicate a hydride transfer event or simply that the QM workflow is better at estimating the thermodynamic stability as noted before both radical and carbocation stability follow the same rule of thumb.