lies very much to the right.
The equilibration in the solid phase in the dark is very slow at room temperature, while in acid
solution without the exclusion of light it is a question of hours.
Absorption spectra in the visible and UV spectral region of solutions are difficult and uncertain
because the equilibration is catalysed by light and acid, so other evidence of the identity and purity
of the two isomers has to be given.
IR-spectroscopy (4000-400 cm-1
) is suited for that purpose because the Co-O-N-O and the Co-N-O
fragments have different vibrational patterns.