Using IR and Raman spectra to explain the catalytic activity of the Fe(II)/Fe(III) pair toward the cleavage of peptide bonds.

IR and Raman experiments of formamide (FA) solutions containing variable amounts of Fe(II) and Fe(III) salts were carried out. The νCO vibration is downshifted whereas the νCN mode is upshifted in the presence of the divalent ion. As the trivalent ion is added to the solvent, upshifts of both νCO and νCN vibrations are observed.

A purely vibrational insight on the tetragonal distortion of [Cu(DMF)6](2+).

Raman spectra of N,N-dimethylformamide (DMF) solutions containing copper perchlorate at different compositions have been recorded. The spectral changes exhibited at the rmethyl region of DMF, in the presence of the Cu(II) salt, were reported for the first time. A correlation with the δOCN region is made.

A Raman study on preferential interactions in the formamide/pyridine/pyridazine system and complementary thermodynamic information on the formamide/pyridazine mixture.

The formamide (FA)/pyridine (py)/pyridazine (prd) system was investigated by FT-Raman spectroscopy and the results in situ show that FA is preferentially bound to py, as experimentally pointed out by the proton affinity (PA) values of these azabenzenes. Temperature-dependent further investigations for the FA/prd mixture clearly show that the 2:1 FA:prd complex is more stable than the 1:1 FA:py adduct, even though its formation is influenced by the extremely negative entropy of the system, which becomes the spontaneously unfavorable global process. Linear relationships of the complex formation enthalpies (ΔH°) with band shifts (Δν) and dipole moments (μ) of these azabenzenes are observed and are in excellent agreement with our recent studies.

FT-Raman spectroscopic analysis of the most probable structures in aluminum chloride and tetrahydrofuran solutions.

A study by concentration-dependent Raman spectroscopy is presented for solutions of AlCl(3) in THF. The formation of small amounts of AlCl(4)(-) has been evidenced by the appearance of only one band at 348 cm(-1) in the most diluted salt solution. Another band at 330 cm(-1) starts rising with increasing salt concentration and it seems to belong to the [AlCl(3)(THF)(3)] complex.

Using vibrational and electronic spectroscopies to investigate different complexes in the formamide/nickel chloride system.

Raman, IR and UV-vis-NIR experiments of formamide (FA) and nickel chloride solutions at different compositions were carried out. The quantitative Raman study at the νCN region shows that 5 FA molecules are coordinated to Ni (II) and the sixth position of the octahedron is occupied by one chloride, with preferential formation of [Ni(FA)5Cl]Cl in concentrations near 0.1 mol kg(-1).

Lewis acid-base adducts: a quantitative Raman analysis of formamide and dimethylsulfoxide mixtures.

Raman spectra of pure liquid dimethylsulfoxide (DMSO) and of binary mixtures of formamide (FA) and DMSO in different compositions were obtained. The vibrations involving the SO functional group in the band envelope at ca. 1050 cm(-1) of pure liquid DMSO are assigned to monomers, dimers and higher aggregates of DMSO.

Vibrational studies on the selective solvation of Na+ and ClO3- ions in dimethylformamide-formamide mixture.

Raman and infrared spectra of sodium chlorate in binary mixture of N,N-dimethylformamide (DMF) and formamide (FA) were obtained. The addition of FA to the NaClO3-DMF system allow us to observe a new band at 1709 cm-1. This has been possible since the large dissociation of Na+ and ClO3- ions produced by the addition of FA helps to observe the coordination effect of DMF on the Na+ ions, in full agreement with the Gutmann donor number of this later.

Formation of high concentrations of BrO(2) in acidic bromate solutions.

A new procedure to produce the BrO(2) transient species allowed time-resolved UV-vis spectra that show a structured band (lambda(max) = 502 nm) in dichloromethane to be obtained. In water, because of the increase of the dielectric constant, the lambda(max) presents a blue shift to 474 nm and the species decomposes much faster. The time-resolved spectra show evidence for its equilibrium with a nonidentified colorless form.

Vibrational investigation of the stretching region of bromate ion in solution.

The splitting of v1 (794 cm(-1)) and v3 (805 cm(-1)) modes in the stretching region of the bromate (C3v) was observed for the first time in dimethyl sulfoxide (DMSO) using vibrational spectroscopy. Depolarization measurements allowed to assign the asymmetric and symmetric modes in solution. The band at 805 cm(-1) that has been attributed to the symmetric stretching mode (A1) corresponds in fact to the asymmetric stretching mode (E) and the band at 794 cm(-1) corresponds to the symmetric stretching mode (A1).