Figure 1. Atomic structure of P/AGNR-11 complex in O2 coordination. The distance between the fragments is 3.7 Å. Carbon atoms of AGNR-11 are denoted in white, carbon atoms of P are denoted in purple, hydrogen atoms are denoted in blue.

The relative energies of spin states of FeP/AGNR are presented in Table 2. It was found that among 3 possible spin states (singlet, triplet, quintet), the Fe d ⁶ triplet state with two unpaired electrons in d_yz andd_xz orbitals (Figure 2) is energetically preferable, which coincides with previous theoretical data¹⁹ at GGA PBE level of theory. The energy differences between triplet and singlet and triplet and quintet states in infrared energy region (40 and 28 kcal/mol, respectively) directly indicate possible optical activity and spin-flip transitions in FeP complex atop AGNR.

Table 2. Relative energies of the FeP complex in different spin states.