Metastable isonitrosyl structure of the nitroprusside anion confirmed by nuclear inelastic scattering

Nuclear inelastic scattering measurements were performed on a guanidium nitroprusside ((CN3H6) (Sub 2) [Fe(CN)(Sub 5)NO], GNP) monocrystals at 77 K after the sample was illuminated with blue light at 50 K to populate the two metastable states, MS1 and MS2, of the nitroprusside anion. Comparison of experimental nuclear inelastic scattering spectra, which have been recorded under conditions excluding and including the metastable MS1 state, with simulated NIS spectra using density functional theory, strongly supports the isonitrosyl structure of the metastable MS1 state as proposed by