Photoelectron spectra of alkyldiaziridines

Abstract

Hel photoelectron (PES) spectra have been obtained for six trisubstituted and three tetrasubstituted diaziridines: 1,3,3-trimethyldiaziridine (1), 1-isopropyl-3,3-dimethyldiaziridine (2), 1-methylspiro-[diaziridine-3,1′-cyclopentane](3), 1-benzyl-3,3-dimethyldiaziridine (4), 3-benzyl-1,3-dimethyl-diaziridine (5), 3,3-dibenzyl-1-methyldiaziridine (6), tetramethyldiaziridine (7 or Me-1), 1-benzyl-2,3,3-trimethyldiaziridine (8 or Me-4) and 3-benzyl-1,2,3-trimethyldiaziridine (9 or Me-5). Analysis provided information about the outer valence electronic structures and geometric conformations. The observed splitting of the n⁺ and n^– ionization events indicates that all compounds exist in trans configurations; the lone pair–lone pair dihedral angle is 100 ⩽θ/deg ⩽ 110; and θ decreases with substitution. The centre of gravity of the two lone-pair ionizations remains fairly constant at E= 9.5(9.15) eV for trialkyl (tetraalkyl) substitution. N-Alkylation has a much greater effect on the electronic structure of diaziridine than does C-alkylation. The additional phenyl group of benzyl substituents and the p-methoxyphenyl group of 1-(p-methoxybenzyl)-3,3-dimethyldiaziridine (10) exert negligible influences. The 1,3-trisubstituted diaziridine 10 decomposes thermally to form NH₃, a reaction described previously only for 3,3-dialkyl- and 1,2,3-trialkyl-diaziridines.