Finally, it has to be stressed that it is not possible to assess the π-resonance structure and the localized/delocalized bonding patterns in PCT and its anions based solely on their magnetic-response properties. This is mainly because within the framework of the molecular orbital (MO) theory of the polyatomic systems chemical bonding should always be regarded as an effect of interference of all occupied MOs (due to their intrinsic delocalized nature). However, the induced global ring current densities are determined mostly by the electron transitions within a narrow frontier MO window, which can be rationalized by the symmetry-based selection rules by Fowler and Steiner. Consequently, the global diatropic and paratropic ring currents in PCT 2-and PCT 4- represent the cyclic charge transfers of only two and four π-electrons, respectively, induced by the external magnetic field, and as such they bring clearly not enough information to decipher the distribution of all π-electrons over the σ-bond skeleton (and to assess their localized/delocalized character). In other words, despite coincidences between the "4n + 2" and "4n" rules by Hückel and the symmetry-based selection rules by Fowler and Steiner it is generally not possible to assess (anti)aromaticity and its origins from the magnetically-induced ring-current models in molecular topologies other than simple annulene-type cycles. Moreover, in the charged PCT systems, the magnetically-induced global ring currents appear to be less chemically meaningful than the local circulations hidden in the ring-current spectrum, at least in the context of the π-aromatic stabilization effects. Indeed, the characteristic pattern of weak local circulations featuring neutral PCT (and interpreted in terms of local aromaticity in the benzene units) is also present inside the ring current spectra of PCT 2-and PCT 4-, although it is almost entirely concealed by the much stronger global circulations over the envelope pathways (Figure ). Furthermore, spectral decomposition of the chemical shifts of benzenoid protons reveals that the average magnetic shielding caused by the local circulations decreases gradually from the aromatic to quasi-olefinic region in the 1 H NMR spectrum, i.e., from 7.6 ppm (PCT) through 6.7 ppm (PCT 2-) to 5.6 ppm (PCT 4-). Importantly, these changes are directly proportional (R 2 = 1.0000) to the corresponding changes of HOMA presented in Figure , which reaffirms validity of the proposed Clar structures.