To gain more insight into the formation of cobalt(III) carbene radical complex 2 under the influence of light, additional experimental and computational studies were performed. In absence of benzophenone, complex 1 was dissolved in DCM-d2 and its conversion was monitored by NMR spectroscopy (Figure ). Under dark conditions, the concentration of complex 1 remains constant (see supporting information, Figure ). Next, complex 1 was irradiated by using a light probe attached to the NMR machine, while the NMR spectra were measured over time. Because complex 1 mainly absorbs within the visible light region (for UV-Vis absorption spectrum, see Figure ), a 390-500 nm light source was used. We observed that complex 1 decreases exponentially upon irradiation of light (Figure ), indicating that this process is not solely limited by the input of photons. Additionally, the formation of [Co II (TPP)] was observed, suggesting that the Co-C bond in complex 1 is homolytically cleaved, instead of the C-H bond. This results into the formation of a dimethyl malonate radical and [Co II (TPP)] (Figure , left). We suspected that this malonate radical can abstract a hydrogen atom from a second molecule of complex 1 (Figure , right), forming the cobalt(III) carbene radical complex that was observed with EPR spectroscopy (see above). Further evidence for this hypothesis was found when we plotted 1/[Complex 1] versus time and observed a linear trend in the conversion of complex 1, which is close to a second order relationship (Figure , R 2 = 0.96). This suggests that the conversion of complex 1 is influenced by two reactions: i) the homolytic cleavage of the Co-C bond, and ii) the HAT via the formed malonate radical. However, the first reaction must occur before the second reaction can transpire. Therefore, the derivation of the reaction order kinetics is not unambiguous. Yet, the observed linear relationship indicates that two molecules of complex 1 lead to its conversion.