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

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 (NH₂NH^-) are presented. These results provide strong confirming evidence for Berkowitz's recent determination of the N-H bond strength in hydrazine.