Showing papers by "Enrique J. Baran published in 1992"

Raman, pre-resonance Raman and electronic spectra of iron(II) saccharinate

Abstract: The Raman spectrum of solid [Fe(Sac) 2 (H 2 O) 4 ].2H 2 O was recorded and assigned. Some comparisons with the spectra of the related copper(II) and nickel(II) complexes were also made. The excitation profiles of the vibrational modes that show pre-resonance on excitation with laser lines within the electronic bands are reported. On this basis, and with the aid of a semi-empirical extended Huckel MO calculation, the assignment of the metal-ligand vibrations and the interpretation of the electronic spectrum could be reinforced

Raman, pre‐resonance Raman and electronic spectra of the anion [VO2Q2]− (Q = 8‐hydroxyquinolinate)

Abstract: The Raman spectrum of Na[VO 2 Q 2 ] was recorded and assigned by comparison with related species. The excitation profiles of the vibrational modes that show pre-resonance on excitation using laser radiation within the electronic bands are reported and three different types of profiles could be found. The electronic spectrum of the anion was also recorded and interpreted with the aid of a semi-empirical MO calculation. This calculation, together with the results of the pre-resonance experiments, also reinforced some of the vibrational assignments

Vibrational spectrum of Zn2 VO(PO4)2

Abstract: The infrared and laser Raman spectra of Zn 2 VO(PO 4 ) 2 were recorded and are briefly discussed with the aid of a factor group analysis. Some interesting aspects related to the strongly condensed nature of the phosphate groups and to the characteristics of the V=O bonds in this structure are also considered

Infrared, Raman and pre‐resonance Raman spectra of vanadyl(IV) tetraphenylporphyrin

Abstract: The infrared and Raman spectra of vanadyl(IV) tetraphenylporphyrin were recorded between 1600 and 200 cm -1 . Assignment of most of the vibrational modes was done by comparison with other related compounds. The V-N and V=O metal-ligand vibrations could be clearly identified. Pre-resonance experiments were performed, using different radiation from an argon ion laser, in the energy range between the main electronic transitions of the complex [the Soret band and the (α+β) doublet]. Analysis of the excitation profiles suggests that all the enhanced bands contribute to both the A and B terms of Albrecht's equation

Über die Wechselwirkung des Vanadyl(IV)-Kations mit Calcium-Hydroxylapatit

Abstract: Abstract Solid products obtained from calcium hydroxylapatite suspensions in diluted VO2+ solutions, under different experimental conditions, were investigated by means of X-ray powder diffractometry and IR and ESR spectroscopy. It is demonstrated that the VO2+ cation cannot be incorporated into the apatite-lattice but is strongly adsorbed on the surface of the material. Different aspects of this adsorption were thoroughly investigated. The ESR spectra suggest an inhomogeneous distribution of the adsorbed species and the generation of O = V (O)4 moieties, which show a high stability towards oxidation.

Mean Amplitudes of Vibration of the Novel XeF‐ 5 Anion.

Abstract: The first example of a chemical species adopting the unusual pentagonal planar geometry was the anion XeFj, reported in 1991 [1], Recently, Christe et al. [2] reported the existence of the IF|~ dianion, which is only the second known example of such a molecular geometry. In order to advance in the characterization of this very interesting species, we have now undertaken a calculation of its mean amplitudes of vibration and compared the results with those obtained for some related molecules and ions. The calculations were performed using the method of characteristic vibrations of Muller and co-workers [3-5], The vibrational frequencies were taken from [2] and an F I F angle of 72° was assumed. The mean amplitudes of vibration calculated for IF|~, in the temperature range between 0 and 1000 K, are presented in Table 1. For comparative purposes, Table 2 shows the corresponding values for the isoelectronic XeFJ anion [6] and other closely related species. The amplitude value for the I F bond in IFf~ is, as expected, appreciably higher than that of the X e F bond in XeFJ, in agreement with the additional negative charge present over the iodine species and its lower nuclear charge. These two factors evidently produce an enhancement of the I F bond polarity, generating a weakening of these bonds [2], which can also be visualized from the strong temperature dependence of its amplitude values (see Table 1), which in this case is yet more important than in XeFj [6]. On the other hand, the very strong temperature dependence also observed for the non-bonded in-plane