We utilised ultrafast transient absorption (TA) spectroscopy to unravel the nature of the excited state species involved. We performed measurements of Sc(OTf)3 in MeCN under both O2 and N2 atmospheres (purging for 30 minutes, followed by gassing with N2 in a purity of 99.99%). Initially, measuring a solution of Sc(OTf)3 in MeCN under an inert N2 atmosphere resulted in a strong bleach signal at approximately 500 nm, accompanied by weak excited-state absorption (ESA) features (Fig. ). This bleach rapidly converted into a positive signal over a slower time scale of a few nanoseconds. The positive signal then continuously grew over the microsecond time scale until reaching a maximum of around 1 microsecond, after which it faded slowly, as depicted in Figs. . In the presence of O2, similar kinetic behaviour was found at the early stage, but with a feeble TA signal, and only during the long timescale (microseconds, the decay was somewhat faster than this in the N2 atmosphere) (see Fig. ). The initial bleach signal at 500 nm was assigned to the initial fluorescence of the Franck-Condon (FC) state, which quickly relaxed to some nonemissive state (S1 relaxed); this took 300 fs. This relaxed state populated another state, the triplet state, at a slow rate (10 ns). The triplet state was then slowly quenched over a microsecond lifetime. The weak invariance between the N2 and O2 atmosphere was attributed to the O2 that was strongly bound to the Sc 3+ complex and present even under the N2 atmosphere because of strong Sc oxophilicity. A role for the triplet state of O2 in the population of the Sc 3+ complex triplet state was highly expected. When measured in toluene/MeCN (Figs. ), the transient absorption data were changed to a greater extent than those in pure MeCN, but remained similar under O2 and N2 atmospheres. For instance, the initial fluorescence from FC was missing, but a fast lifetime decay of 500 fs (due to the relaxation state) was present, followed by a lifetime rise of 20 ps that was assigned to the early formation of the triplet state (see Fig. ). Within 20 ns, the bleach signal around ca. 500 nm started to evolve again, followed by an increase in the overall ESA features across the visible region over 90 ns. The appearance of the bleach signal was assigned to the delayed fluorescence of the Sc complex, which can happen due to the reversible ISC (r-ISC) process from the triplet to the singlet state, as depicted in Fig. . Due to the presence of toluene molecules, an ET was expected to occur from toluene to the Sc complex on a time scale of 90 ns, leading to the disappearance of the fluorescence peak and formation of S1 -state, as evident from Fig. . The recombination of this reduced state to the S0 state occurred at a slow rate > 1.2 microseconds. The absence of toluene remarkably affected the Sc complex behaviour by delaying the triplet state formation in MeCN vs in the MeCN/toluene mixture. The insensitivity of the Sc complex towards the O2 atmosphere also highlighted the role of strongly bound O2 molecules in extending the lifetime of the observed excited states. For instance, the slow decay of the S1 - state was expected to be due to structural rearrangements within the Sc complex, leading to the desorption of the reduced O2 into the reaction mixture for further use in product formation pathways.