Infrared spectrum of the hyponitrite dianion, N2O22-, isolated and insulated from stabilizing metal cations in solid argon

Article abstract of DOI:10.1021/ja0029331

Ultraviolet irradiation of a rigid 7 K argon matrix containing alkali or alkaline earth metal atoms and (NO)₂ isolated from each other by one or two layers of argon forms N₂O₂^2- dianions insulated from two M⁺ cations by argon atoms, and visible photolysis reverses this electron-transfer process likely involving the N₂O₂^- anion intermediate. The isolated N₂O₂^2- dianion is identified from isotopic substitution and isotopic mixtures, which show that the new 1028.5 cm^-1 metal independent absorption involves two equivalent NO subunits. DFT calculations predict a strong 1078.1 cm^-1 fundamental for the Li(NO)₂Li molecule and isotopic frequency ratios in excellent agreement with the observed values, which provides a model for the matrix dianion system. The spectrum of solid Na₂N₂-O₂, exhibits a 1030 cm^-1 infrared band, which strongly supports the present N₂O₂^2- dianion assignment. The electrostatic stabilization of N₂O₂^2-, which is probably unstable in the gas phase, is made possible by metal cations separated by one or two insulating layers of argon in the rigid 7 K matrix.