Inter-channel effects in monosolvated atomic iodide cluster anion detachment: correlation of the anisotropy parameter with solvent dipole moment

Photoelectron imaging results are presented for I(-)[middle dot]X cluster anions (X = CO(2), C(4)H(5)N [pyrrole], (CH(3))(2)CO, CH(3)NO(2)). The available detachment channels are labeled according to the neutral iodine atom states produced (channel I ≡ (2)P(3/2) and channel II ≡ (2)P(1/2)). At photon energies in the vicinity of the channel II threshold these data are compared to previously reported results for I(-)[middle dot]X (X = CH(3)CN, CH(3)Cl, CH(3)Br, and H(2)O). In particular, these results show a strong connection between the dipole moment of the solvent molecule and the behavior of the channel I photoelectron angular distributions in this region, which is consistent with an electronic autodetachment process. The evolution of the channel II:channel I branching ratios in this excitation regime supports this contention.     

The correlation of intermolecular effects in the vibration spectra of BF3 with alterations in its quadratic valence force field

The effect of weak and specific intermolecular interactions in the vibration spectra of molecules is considered and correlated with alterations in the potential energy of the molecule via the force field. The approach, which follows a previously developed method [3], shows how best to choose the perturbations in order to reproduce the intermolecular interaction and keep the internal consistency of the force field. The vibrational calculation is exemplified for XY₃molecules with D_3h symmetry and applied to the boron trifluoride molecule.     

Theory for the atomic shell structure of the cluster magnetic moment and magnetoresistance of a cluster ensemble

We present a simple theory for the cluster size dependence of the average cluster magnetic moment of transition metal clusters. Assuming a local environmental dependence of the atomic magnetic moments, the cluster magnetization exhibits a magnetic shell structure, reflecting the atomic structure of the cluster. Thus, the observed oscillations of the average cluster magnet moment may serve as a fingerprint of the cluster geometry. We also discuss the giant magnetoresistance (GMR) exhibited by an ensemble of magnetic clusters embedded in a metallic matrix. It is shown that the magnetic anisotropy affects strongly the magnetization of the cluster ensemble under certain conditions. Since the GMR depends on the cluster ensemble magnetization, it can be used to determine the cluster magnetic anisotropy energy.     

The proton magnetic resonance spectra of d-aldosterone and its acetylated derivatives

PMR spectra of d-aldosterone, its acetylated derivatives and related compounds were studied using 60 and 100 MHz spectrometers at various temperatures, in CDCI₃, DMSO-d₆, CD₃OD and D₂O. The aldehyde form ( 1 ) was not found. The solutions of d-aldosterone and aldosterone-21 acetate contain a mixture of the cyclic forms with one (11–18) hemi-ketal bridge ( 2 ) and two (11–18, 18–20) hemi-ketal bridges ( 3 ). Preliminary results concerning modifications of the relative concentration of 2 and 3 obtained by varying solvents and temperature are given. Aldosterone-diacetate exists in only one form, most likely form 2 . There is restricted rotation of the group at C-21 in d-aldosterone and in form 3 of aldosterone 21-acetate. One molecule of water is probably bound to d-aldosterone.     

Reactivity of oxidized substances and its correlation with catalyst properties in deep oxidation reactions

In terms of the donor-acceptor interaction concept /1/ the relative reactivity (RR) of organic and inorganic compounds and its correlation with catalyst properties in deep oxidation reactions are treated. RR and relative activity of the catalysts are shown to change depending on the predominant character (acceptor or donor) of reactant-catalyst interaction.

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- /1/ (OPC) . , OPC .

     

The correlation of proton affinities with atomic charges and electronegativities for the group 14 to 17 hydrides

Proton affinities for hydrides of formula $\mathrm{AH}^{-}_{n-1}$ containing the elements A from the second to the fifth period of the periodic table and groups 14 to 17 are predicted at the Hartree–Fock, MP2 and B3LYP levels of theory employing both core potential basis sets and the 3‐21G basis set. The core potential methods perform well when compared with all electron calculations using the 3‐21++G** basis set. The proton affinities of the hydrides containing elements from groups 15 and 16 of the periodic table are more accurate than those with elements from groups 14 and 17. A cancellation of errors appears to occur more completely if the protonated and nonprotonated molecules contain both bond and lone pairs before and after the protonation reaction. Proton affinities correlate nearly linearly with the atomic charges on the hydrogen atoms when these charges are determined by the generalized atomic polar tensor (GAPT) method. This tendency can be associated, in principle, with the group electronegativities as introduced by Iczkowski and Margrave. © 2000 John Wiley & Sons, Inc. J Comput Chem 21: 1119–1131, 2000     

Pressure response of Raman spectra of water and its implication to the change in hydrogen bond interaction

In situ Raman spectroscopic measurements of water in the region of OH vibration were conducted up to 0.4 GPa at 23 and 52 degrees C. The frequencies of the decomposed OH stretching bands initially decreased with increasing pressure, reached a minimum at 0.15 GPa and increased up to 0.3 GPa and then decreased, which corresponds to the variations of the strength of hydrogen bonding. This variation was observed at 23 degrees C, but not at 52 degrees C, which suggests a change in pressure dependence on the hydrogen bond interaction between these two temperatures. Based on the equilibration model between hydrogen-bonded and nonhydrogen-bonded molecules, the present experimental results indicate that the pressure variation of the viscosity depends on the ratio of hydrogen-bonded molecules, rather than the strength of hydrogen bonding between molecules.     

The spectra of 3-OXO-2, 3-dihydrothianaphthene and its derivatives

Condensation of isatin--anil with acetylacetone and with derivatives of malonic and acetoacetic acids in acetic anhydride has given 5 indogenides. It is observed that isatin--anil is readily acetylated by acetic anhydride. The acetyl derivative is very reactive, and is an intermediate in the condensation of isatin--anil with acetylacetone in acetic anhydride. The indogenides which have been synthesized are nonphototropic as a result of the presence of intramolecular hydrogen bonds.For part IX, see [1].     

Stark effects in gas-phase electronic spectra. Dipole moment of aniline in its excited S(1) state

Measurements of the Stark effect on the rotationally resolved S(1)<--S(0) fluorescence excitation spectrum of aniline are reported, providing quantitative information about the degree of charge transfer in the electronic transition. We find that mu(a)(S(1)) = 2.801 +/- 0.007 D, a value that is approximately 150% larger than the ground state, mu(a)(S(0)) = 1.129 +/- 0.005 D. The enhanced value of the dipole moment in the S(1) state is attributed to more efficient electron donation by the quasi-planar amino group to the aromatic ring.     

Long-wave absorption band and magnetic susceptibility of nickel phthalocyanine in relation to its degree of oxidation

A study has been made of the electronic absorption bands in the IR spectral region and the room-temperature magnetic susceptibility of polycrystalline layers and powders of nickel phthalocyanine after oxidation by halogen vapors. The polarization of the long-wave electronic band corresponds to the hypothesis of light absorption by conduction electrons. It has been shown that the magnitude of the magnetic susceptibility of the oxidized samples is independent of their degree of oxidation, and an explanation for this lack of dependence is given within the framework of Hubbard's model.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 5, pp. 534–539, September–October, 1989.     

Two-dimensional cross-spectral correlation analysis and its application to time-resolved Fourier transform emission spectra of transient radicals

A spectral analysis method, based on the generalized two-dimensional (2D) vibrational spectra correlation analysis, is developed for deciphering the correlation among the spectral peaks of two different spectra. This 2D cross-spectral correlation (2DCSC) analysis is aimed at revealing the vibrational features associated with a common species in two spectra, each obtained from a system containing multiple species with at least one common species. The cross-spectral correlation is based on the premise that the spectral features of the same species should have the same time and frequency responses toward similar perturbations. The effectiveness of the cross-spectral correlation analysis is first illustrated with model systems, with spectral peaks decaying linearly or exponentially with time, before being applied to analyzing time-resolved emission spectra obtained, by a Fourier transform IR spectrometer, for samples consisting of the vibrationally excited transient cyanooxomethyl radical (OCCN). 2DCSC among the three different sets of time-resolved spectra collected following the photodissociation of three different precursor molecules of OCCN, respectively, allows the identification of the CN and CO stretching modes of this radical.     

The electronic structure of polyfluorinated carbonyl compounds and correlation with ir spectra and reactivity

Calculations of electronic structure, force constants and anharmonicity constants of the C-O valence vibration for a number of fluorinated ketones and ethers have been performed by the CNDO/SW and CNDO/2 methods. The change of association constants for these molecules with phenol is qualitatively explained. Anomalies in the IR spectra are studied, the role of direct fluorine - oxygen interactions is considered. The inductive constants for H(CF₂)₂, and C1(CF₂)₂, are calculated.     

Kinetics of β-picoline oxidation to nicotinic acid over vanadia-titania catalyst. 3. The oxidation of nicotinic acid

The oxidation of nicotinic acid (NA) over binary vanadia-titania catalysts with different contents of residual sulfate ions (0.2 and 2.8 wt. %) was studied at 250–300°C in the feed reaction mixture of the composition NA: O₂: H₂O = 0.01–0.17: 5–20: 0–20 (vol. %), with nitrogen as a balance. The kinetic parameters of the process were determined. It was shown that even a ten-fold increase in the content of residual sulfate ions in the samples has no significant effect on the kinetics of the NA oxidation.     

Higher approximations for transition matrices and their application to the calculation of atomic spectra

Theoretical and Experimental Chemistry -