Jesus, A. J. LopesNunes, Claudio M.Ferreira, Gil A.Keyvan, KiarashFAUSTO, RUI2024-09-252024-09-252024Lopes Jesus, A. J., Nunes, C. M., Ferreira, G. A., Keyvan, K., & Fausto, R. (2024). Photochemical Generation and Characterization of C-Aminophenyl-Nitrilimines: Insights on Their Bond-Shift Isomers by Matrix-Isolation IR Spectroscopy and Density Functional Theory Calculations. Molecules, 29(15), 3497.https://doi.org/10.3390/molecules29153497https://hdl.handle.net/11413/9246The intriguing ability of C-phenyl-nitrilimine to co-exist as allenic and propargylic bond-shift isomers motivated us to investigate how substituents in the phenyl ring influence this behavior. Building on our previous work on the meta- and para-OH substitution, here we extended this investigation to explore the effect of the NH2 substitution. For this purpose, C-(4-aminophenyl)- and C-(3-aminophenyl)-nitrilimines were photogenerated in an argon matrix at 15 K by narrowband UV-light irradiation (lambda = 230 nm) of 5-(4-aminophenyl)- and 5-(3-aminophenyl)-tetrazole, respectively. The produced nitrilimines were further photoisomerized to carbodiimides via 1H-diazirines by irradiations at longer wavelengths (lambda = 380 or 330 nm). Combining IR spectroscopic measurements and DFT calculations, it was found that the para-NH2-substituted nitrilimine exists as a single isomeric structure with a predominant allenic character. In contrast, the meta-NH2-substituted nitrilimine coexists as two bond-shift isomers characterized by propargylic and allenic structures. To gain further understanding of the effects of phenyl substitution on the bond-shift isomerism of the nitrilimine fragment, we compared geometric and charge distribution data derived from theoretical calculations performed for C-phenyl-nitrilimine with those performed for the derivatives resulting from NH2 (electron-donating group) and NO2 (electron-withdrawing group) phenyl substitutions.eninfo:eu-repo/semantics/openAccessAttribution-NonCommercial-NoDerivs 3.0 United Stateshttp://creativecommons.org/licenses/by-nc-nd/3.0/us/Bond-shift IsomersC-aminophenyl-nitriliminesDFT CalculationsIR SpectroscopyMatrix-isolationPhotochemistryArticle0012878465000012-s2.0-85200780989391249021420-3049