Magnetic criteria of aromaticity in a benzene cation and anion: how does the Jahn–Teller effect influence the aromaticity?

Insights on the Reactivity of Terminal Phosphanido Metal Complexes toward Activated Alkynes from Theoretical Computations

“…Among other criteria, it is known that nucleus-independent chemical shift values calculated 1 Å above the corresponding RCPs (NICS(1)), black dots in Figure , provide a good measure of the aromaticity/π electron delocalization along a ring. , Typical NICS(1) values, in parts per million, are ca. −10.2 for benzene, the paradigm of an aromatic ring, , −10.1 for pyridine, , and −10.8 (rings 1 and 2) and −8.4 (ring 4) for isolated phen . In this work, NICS(1) values for phen at [Re­(PPh 2 ) (CO) 3 (phen)] (−10.1, −10.3, and −8.7 ppm for rings 1, 2, and 4 in Table S10, respectively) are similar to those mentioned above for the isolated ligand.…”

“…21,22 Typical NICS(1) values, in parts per million, are ca. −10.2 for benzene, the paradigm of an aromatic ring, 23,24 −10.1 for pyridine, 25,26 and −10.8 (rings 1 and 2) and −8.4 (ring 4) for isolated phen. 23 In this work, NICS(1) values for phen at [Re(PPh 2 ) (CO) 3 (phen)] (−10.1, −10.3, and −8.7 ppm for rings 1, 2, and 4 in Table S10, respectively) are similar to those mentioned above for the isolated ligand.…”

Magnetic criteria of aromaticity

“…Thus, a CAS search of the topic ''Magnetic susceptibility exaltation'' in the last ten years yielded 51 results. None of them is an experimental measurement of the properties and most of them are used as computational evidence for aromaticity of the studied compounds, mainly in comparison to other criteria of aromaticity, such as the recent demonstration by Andjelkovic et al 24 Since the experimental measurement of magnetic susceptibility exaltation is almost non-existent and computationally there are better methods for assessing aromaticity (see below), this topic will not be further discussed here.…”

1,10-Phenanthroline ring-opening mediated by cis-{Re(CO)2} complexes

“…Keeping in mind that typical NICS(1) values, in parts per million ( ppm), are ca. −10.2 for benzene, 21,22 or −10.1 for pyridine, 23,24 our computations do not show significant differences in the NICS(1) values of both complexes. As expected, pyridine (NICS(1) = −9.4/−9.1 ppm, for IIIa/IIIa′ respectively) and imidazole (NICS(1) = −9.1/−9.2 ppm, for IIIa/IIIa′ respectively) show notably larger π-electronic delocalization than that of the cyclopentadienyl (NICS(1) = −3.3/−3.7 ppm, for IIIa/IIIa′ respectively) rings.…”