Conjugate base of a cyclic hydrazine: formation and energetics of N-diaziridyl anion

Abstract

N-Diaziridyl anion ( 1), the conjugate base of a simple hydrazine, has been generated in a Fourier transform mass spectrometer (FTMS) by reduction of the nitrogen–nitrogen double bond in diazirine. The acidity of its conjugate acid (390 ± 3 kcal mol −1) and the electron affinity of its corresponding radical (0.50 ± 0.10 eV) were measured. These data are combined in a thermodynamic cycle to afford the N–H bond strength in trans-diaziridine ( 2, 88 ± 4 kcal mol −1). This value represents one of the few such bond energies reported for a hydrazine. High-level ab initio complete basis set-quadratic configuration interaction/atomic pair natural orbital (CBS-QCI/APNO) calculations on 1 and the parent hydrazyl anion (NH 2NH −) are presented. These results provide strong confirming evidence for Berkowitz’s recent determination of the N–H bond strength in hydrazine.