Molecular orbital energies (E_HOMO and E_LUMO, eV), gap energies (E_g, eV), total energy (E_Tot, hartrees), and relative energy (ΔE_Rel, 10⁴ kcal mol⁻¹) of 4a, 4b and 5a–5f compounds calculated at PBE0/aug-cc-pVTZ level of theory.

Compound	E HOMO	E LUMO	E g	E Tot	ΔERel
4a	−6.523	−1.700	4.823	−611.1178	22.90
5a	−6.317	−1.633	4.683	−900.8969	4.72
5b	−6.330	−1.636	4.693	−861.6120	7.18
5c	−6.333	−1.640	4.694	−862.8067	7.11
4b	−6.250	−1.705	4.545a	−686.3014	18.18
5d	−6.078	−1.629	4.449	−976.0815	0.0
5e	−6.090	−1.633	4.458	−936.7966	2.47
5f	−6.087	−1.635	4.452	−937.9912	2.39

^a E _g-reported = 4.154 eV.²⁹