The reaction of iodine with 9-methylacridine: formation of polyiodide salts and a charge-transfer complex

Abstract

The reaction of iodine and 9-methylacridine in methylene chloride results not in the formation of a charge-transfer complex as with acridine, but in the iodine-rich salt [ICH 2 C 13 H 8 N-H] 4 (I 8 )(I 5 ) 2 , 8, where a proton on the methyl group has been replaced by an iodine. In toluene, the reaction produces both a charge-transfer complex ICH 2 C 13 H 8 N-I 2 , 9, and a salt [CH 3 -acridine(H)] 2 (I 7 )(I 5 ), 10. Polyiodide salt formation can be explained by the availability of a facile reaction pathway from the aryl radical cation which results from initial oxidation by I 2 .

Halogen Bonding: A Paradigm in Supramolecular Chemistry

“…[8] In other cases I 2 can work as an amphoteric species, one iodine atom functioning as electron acceptor and the other as electron donor. [9] The use of modules which are better defined and more robust in the pattern of the halogen bonding they inherently tend to form, allows a deeper and more subtle study of the characteristics of this intermolecular interaction. Polyhalogenated carbon derivatives possess these definition and robustness requirements and have already been employed with a wide variety of electron donors.…”

Reactions of pyridyl donors with halogens and interhalogens: an X-ray diffraction and FT-Raman investigation

“…In this context, the reactivity of heterocyclic N-bases L, such as pyridine (Py) and 1,4-diazine derivatives, with halogen and interhalogens has attracted an increasing interest during the last decades, in virtue of the ability of these substrates both to behave as r-donors to give neutral charge-transfer (CT) adducts and to undergo Nprotonation, the resulting cations being counterbalanced by discrete or extended polyhalides frameworks. The vast majority of the products characterised in the literature refers to the reactions of donors of type L with I 2 [13]. In particular, not only a large number of neutral charge-transfer adducts L AE I 2 featuring N-I-I linear groups (L = variously substituted pyridine and derivatives [14], such as 2,2 0 -and 4,4 0 -bipyridine (bipy), pyrazine and derivatives [15][16][17], and acridine [18]) and cationic N-protonated products HL + counterbalanced by iodide anions or polyiodide networks [6] has been reported, but also N-iodopyridinium ions LI + [19], two nitrogen donors coordinated to iodine(I) complexes (L-I-L) + [20], and diiodine molecules bridging two donor units L-I-I-L have been described.…”

Self-assembly of supramolecular architectures based on polybromide anions: crystal structure of [tppz=tetra(2-pyridyl)pyrazine]

“…In fact, it has been shown that, depending on the nature of the halogen and on the reaction conditions, heterocyclic N-bases, such as pyridine (Py) and 1,4-diazine derivatives, react with halogens and interhalogens to give not only neutral charge-transfer (CT) adducts, but also salts where the N-protonated cations are counterbalanced by discrete halide or extended polyhalide frameworks. Protonated cations were found also under anhydrous conditions, but the protonation mechanism was not fully investigated [14]. The oxidation of the aromatic heterocycle to give cationic radical species has been proposed to be responsible for the formation of stable cationic protonated species by solvolysis or reaction with incipient moisture [14].…”

“…Protonated cations were found also under anhydrous conditions, but the protonation mechanism was not fully investigated [14]. The oxidation of the aromatic heterocycle to give cationic radical species has been proposed to be responsible for the formation of stable cationic protonated species by solvolysis or reaction with incipient moisture [14].…”