As postulated above, the split in energy between the two * orbitals, b1 and a2, increases with the electronegativity of heteroatom E as the b1 orbital is lowered more. The 1 3 B1 state is the lowest 3 n,* state for all 6-MR monoheteroaromatics, yet, the computed energy difference to the other  n,* state (1 3 A2) varies from 0.20 eV for 3 to 2.05 eV for 5 (and similarly for the 1 n,* states, except for 3 where 1 1 A2 is 0.42 eV below 1 1 B1). It is, however, notable that the lowest 3 n,* states of 5 and 6 have multiconfigurational character (see T1 diagnostics, Table ). Yet, despite this, the ratios between the MCI values in the n,* and S0 states of 5 and 6 obtained from (U)CAM-B3LYP, (U)CCSD, and (U)BD calculations are quite similar (see Tables , and S5), clarifying that (U)CAM-B3LYP produces reliable estimates of the decrease in aromaticity when going from S0 to the 3 n,* states of these species (see further section 3.6 of the Supporting Information).