Metastable Isonitrosyl Structure of the Nitroprusside Anion Confirmed by Nuclear Inelastic Scattering

Abstract

Nuclear inelastic scattering (NIS) measurements were performed on a guanidium nitroprusside ((CN(3)H(6))(2)[Fe(CN)(5)NO], GNP) monocrystal at 77 K after the sample was illuminated with blue light (450 nm) at 50 K to populate the two metastable states, MS(1) and MS(2), of the nitroprusside anion. A second measurement was performed at 77 K after warming up the illuminated crystal to 250 K where the metastable states decay to the groundstate. The measured spectra were compared with simulated NIS spectra that were calculated by using density functional methods. Comparison of measured and simulated spectra provides strong evidence for the isonitrosyl structure of the metastable MS(1) state proposed by Carducci et al. (Carducci, M. D.; Pressprich, M. R.; Coppens, P. J. Am. Chem. Soc. 1997, 119, 2669-2678).

Dynamical magnetostructural properties of Anabaena ferredoxin

“…This gives rise to resonances only at those frequencies where the modulation is most pronounced, which are the peaks of J( ). Alternatively, the -dependent excitation could be achieved by nuclear inelastic scattering of synchrotron radiation at Mössbauer-active nuclei which is already established for intramolecular vibrational spectroscopy that is sensitive to exclusively those modes that involve Fe nuclei (43,44).…”

Vibrational dynamics of biological molecules: Multi-quantum contributions

“…1) and detailed descriptions of vibrational dynamics [38][39][40][41]23]. The vibrational predictions do not rely on empirical potentials or require prior knowledge of related molecules to constrain the potential.…”

“…Measurements on oriented samples, such as single crystals, also yield the direction of vibrational motions [10,12,14,18,23,20,26,28]. Other names used for this technique include phonon assisted Mössbauer effect [21,22,25,26], inelastic X-ray scattering of synchrotron radiation [11], nuclear inelastic scattering [18], nuclear inelastic absorption [9], and nuclear resonant inelastic X-ray scattering [29].…”

Interpretation of Nuclear Resonant Vibrational Spectra of Rubredoxin Using a Combined Quantum Mechanics and Molecular Mechanics Approach

“…The probability density S(E) for an X-ray photon with energy E to be scattered depends on vectors u k that describe in which way the Mçssbauer nucleus takes part on the kth normal mode (in other words, u k consists of the three iron components of the kth normal coordinate vector). [3] In a low-temperature approximation one can write Equation (1):…”

“…[13][14][15][16] Soon after NRVS emerged, theoretical methods were used to simulate and interpret NRVS spectra. While the spectra of small molecules (containing at most a few hundreds of atoms) were successfully interpreted by quantum-chemical calculations applying density functional theory (DFT), [3,6,11,13,17] the spectra of larger molecules (containing many thousands of atoms) had to be interpreted with normal-coordinate analysis Nuclear resonant vibrational spectra of the reduced and oxidized form of a mutant of rubredoxin from Pyrococcus abyssii were measured and are compared with simulated spectra that were calculated by a combined quantum mechanics (QM) and molecular mechanics (MM) method. Density functional theory was used for the QM level.…”