Hydrolysis and Photolysis of Tris(tetraethylammonium) Pentacyanoperoxynitritocobaltate(III): Evidence for a Novel Complex, Pentacyanonitratocobaltate(III)

Abstract

At pH 2, the rate constant of hydrolysis of tris(tetraethylammonium) pentacyanoperoxynitritocobaltate(III) in H2O is 9.6×10−6 s−1. In the absence of any light, ONOO− is not replaced by H2O and isomerizes within the coordination sphere to NO3−. The novel complex [Co(CN)5NO3]3− released NO3− slowly, as detected by ion chromatography. At pH 6, no hydrolysis is observed. Direct photolysis, both at pH 2 and pH 6, of tris(tetraethylammonium) pentacyanoperoxynitritocobaltate(III) by irradiation (YAG laser) at 355 nm destroys the coordinated ONOO− and releases NO2., which hydrolyzes to NO3− and NO2−. We also measured the 59Co-NMR spectra of [Co(CN)5OONO]3− and [Co(CN)5H2O]2−; the chemical shifts correspond very well to those predicted and are in agreement with the expected contribution to the ligand field by H2O and ONOO−.