In the S 0 state, the π a 2 orbital is doubly occupied. However, the first excited state singlet, S 1 can be thought of as arising from an excitation out of π a 2 , leaving an unpaired electron in this π orbital. Since the S 0 state is multiconfigurational with its unpaired spin distributed between the π b 1 and d x 2 -y 2 orbitals, the electron excited out of π a 2 occupies one of these two orbitals in the S 1 state. Note that in the S 1 state using RASSCF(36e,34o), the configurations (π a 2 ) 1 (π b 1 ) 2 (d x 2 -y 2 ) 1 and (π a 2 ) 1 (π b 1 ) 1 (d x 2 -y 2 ) 2 contribute 71.0% and 8.2% respectively, in the unsubstituted copper corrole (Table ). In the functionalized triphenyl copper corrole, the same two configurations contribute nearly the same amount at 70.8% and 8.7%, respectively. On the other hand, the T 0 state is dominated by a single configuration,