the intermediate triplet states are of mixed LE/CT character. The analysis of the nature of the excited states indeed shows that intermediate triplet states possess a significant LE character (ϕS =0.7 for T2 and T3, see Table and Figures ), different to that of S1, which is more CT in nature. Calculated SOC matrix elements between S1 and the T1 -T3 states (Table ) all show promisingly large values at above 1.0 cm -1 for LE triplet states and between 0.13 cm -1 -0.74 cm -1 for the CT/LE triplet states, indicating possible routes for RISC involving these states. The ΔEST gaps decrease from 0.37 eV to 0.30 eV and 0.26 eV to ΔEST values of 0.33 eV, 0.23 eV and 0.19 eV if the energy difference between S1 and the highest intermediate triplet states are considered, for 4TABN1, 5TABN2 and 6TABN3, respectively. The small singlet-triplet gaps predicted for 5TABN2 and 6TABN3 support the experimentally determined increasing kRISC rate along the series. Further detailed discussion regarding the computations can be found in the Supporting information.