Librational and torsional modes in hydrazinium, N2H 2+6, salts studied by inelastic neutron scattering

Abstract

Inelastic neutron scattering spectra of the hydrazinium dihalides and of hydrazinium sulphate, together with Raman and infrared data on these systems are reported. The internal torsion of the N₂H²⁺₆ ion and the whole body librations both about the N—N axis and perpendicular to it have been identified and are used to calculate the internal and external barriers to rotation. The external barriers are 20–40 % higher than for the corresponding ammonium salts and the internal barrier is considerably less than for the isoelectronic ethane molecule, leading to a predicted torsion frequency for the “free ion” of below 260 cm^–1.