M.E. Chacón Villalba

Infrared evidence of NO linkage photoisomerization in Na2[Fe(CN)5NO]·2H2O at low temperature: experimental and theoretical (DFT) isotopic shifts from 15N(O), 18O and 54Fe species

Infrared spectra of the metastable state I (MSI) of normal and 15NO, N18O and 54Fe isotopically substituted sodium nitroprusside dihydrate (Na2[Fe(CN)5NO].2H2O) have been obtained at 77 K. A comparison of the isotopic shifts measured for the vibrational modes of the FeXY (XY = NO or ON) moiety with those calculated by means of quantum chemistry (DFT) procedures supports the linear Fe-O = N arrangement for the MSI state.

Crystal and molecular structure and photoisomerization of nitropentaamminecobalt(III) nitroprusside sesquihydrate, [Co(NH3)5NO2][Fe(CN)5NO]·1.5H2O

Abstract The crystal structure of nitropentaamminecobalt(III) nitroprusside sesquihydrate, [Co(NH3)5NO2][Fe(CN)5NO]·1.5H2O has been determined by Patterson and Fourier methods employing 3881 independent X-ray reflections with I>2σ(I) and refined by full-matrix least-squares to R1=0.032. The substance crystallizes in the monoclinic C2/c (C2h6) space group No. 15, with a=28.408(3), b=6.422(1), c=22.401(3) A, β=123.55(1)° and Z=8. The metastable state I (MSI) of the nitroprusside anion and the photochemical isomerization reaction of the nitropentaamminecobalt(III) cation to the nitrito isomer were produced by irradiation with Ar+ laser light of 488 nm wavelength at 77 K. TGA and DTA of the non-excited substance were performed under nitrogen atmosphere.

NEW VIBRATIONAL STUDY OF SODIUM NITROPRUSSIDE DIHYDRATE. I. ISOTOPIC DATA FOR 54FE, 13C AND 15N(O) SUBSTITUTED SPECIES

Abstract The Fourier transform infrared and NIR Raman spectra between 4000 and 50 cm−1 of sodium nitroprusside dihydrate, Na2[Fe(CN)5NO]· 2H2O, normal and enriched with 54Fe, 13C and 15N(O), have been obtained. Results provided wavenumbers and isotopic shifts for most of the 33 vibrational modes of the nitroprusside ion, including the stretching bands of both isotopically concentrated and isolated CN and NO groups, as well as the bending bands of FeNO and FeCN groups and core (skeletal) FeC5N stretchings and bendings in isotopically concentrated samples. Assignments of the fundamental vibrations of the [Fe(CN)5NO]2− ion are supported by calculations based on a new force field, to be reported separately.

A new vibrational study of sodium nitroprusside dihydrate. II. A quantum chemistry vibrational study of the nitroprusside anion, [Fe(CN)5NO]2−☆

Abstract A new force field was calculated for the nitroprusside anion, [Fe(CN) 5 NO] 2− , using density functional theory (DFT). This force field was converted to symmetry coordinates and scaled to reproduce the experimental wavenumbers of the normal vibrations. The obtained set of force constants revealed the importance of several interaction constants not considered in previous proposals and allowed a good reproduction of experimental 54 Fe, 13 C and 15 N(O) isotopic shifts, reported in Part I.

Infrared and Raman spectra of -thallium nitroprusside, Tl2[Fe(CN)5NO]

Abstract Interferometric infrared and Raman spectra of thallium nitroprusside (Tl2[Fe(CN)5NO]), with normal isotopic composition or substituted with 13 C (98.5%), were obtained from 4000 to 50 cm−1 at room and low temperature (boiling liquid air). Infrared microscopy used with selected monocrystals allowed the detection of very weak overtone and combination bands. Comparisons are made with other nitroprusside salts, anhydrous and hydrated, and especially with sodium nitroprusside dihydrate.