The Dualistic Nature of -NH3 +, A weak π-Donating,Strong σ-Withdrawing Substituent. Effects on the Intensity of the UV Spectra of the Toluidinium Ions and Related Molecules |
| |
| Authors: | Annick Darry-Henaut Bernard Vidal |
| |
| Institution: | 1. Laboratoire de Spectroscopie de la Réactivité Chimique , UFR de Chimie, Université des Sciences et Techniques de Lille. , 59655 , Villeneuve d'Ascq Cédex , (France);2. Université de La Réunion BP 5 , 97490 , Sainte Clotilde , La Réunion (France DOM) |
| |
| Abstract: | Abstract Hyperconjugation is not restricted to alkyl groups(1–4) and ammoniums interact with π systems through σ-π hyperconjugative coupling(5–9). Their influence on the UV spectrum of the secondary transition of the benzene chromophore in anilinium ions has only been studied during the last years. Previously it was assumed without enough experimental support, that ammonium groups have no spectroscopic effects on a π chromophore (for example:(10,11)). In fact, although it is a strong σ-electronwithdrawing substituent, an ammonium group is a π-donating one 5–8). Its π-donating ability - contrary to what is observed in the corresponding alkyl groups where N is replaced by C - increases whenever the number of N+?C bonds increases, and ?N(CH3)3+ could be as much π-donating as the ?C(CH3)3 group for pseudo-free molecules(5). |
| |
| Keywords: | |
|
|
