The anilino radical Ph—N—H

The phenylnitrenium cation (PhNH+), formally generated upon ionization of the anilino radical, exhibits a singlet ground state ( A ), followed by a triplet state (3A ), with a singlet-triplet energy gap of AESt(P1iNH+) = 0.84 0.1 eV (81 kJmol-1)210,211. 

TABLE 10. Vibrational frequencies (cm-1), infrared intensities, normal modes and potential energy distribution of the anilino radical (C6H5N H). Values obtained from scaled UB3LYP/6-311 + + G(3df,2p) calculations 

FIGURE 24. Normal displacements of vibrational modes of the anilino radical (2A ). The assignment of the normal vibrations and associated frequencies are presented in Table 10. The numbers given within the ring correspond to the modes Q1-Q33 described in Table 10 

We can find a V(N) lone-pair-like basin in the ELF space which, according to the 2.84 e population, involves the nitrogen lone pair and a large part of the unpaired electron. This latter agrees, by a difference of 0.17 e, with that of the integrated spin density however, all other valence basins contain a small amount of the radical population. The Laplacian map of the electron density shows that this monosynaptic valence basin is very compact. 

FIGURE 25 (PLATE 2). Summary of electronic distribution in the anilino radical (2 A ) (a) Bond distances (A), NBO charges [bracket, in au] and Wiberg indices (parentheses, in au). (b) Topology of the electron density determined from atom-in-molecule calculations p(r) = electron density, L = Laplacian of the density defined as L(r) = — V2p(r) and s = ellipticity of the bond critical point, (c) Laplacian map of the density, (d) Isosurfaces of the electron localization function, ELF = 0.87 the values are the populations of the valence basins, (e) Spin density in the molecular plane 

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