Mass analyzed threshold ionization spectroscopy of 7-azaindole cation

The vibrationally resolved mass analyzed threshold ionization (MATI) spectra of jet-cooled 7-azaindole have been recorded by ionizing via four different intermediate levels. The adiabatic ionization energy of this molecule is determined to be 65 462±5 cm⁻¹, which is greater than that of indole by 2871 cm⁻¹. The vibrational spectra of 7-azaindole in the S₁ and D₀ states have been successfully assigned by comparing the measured frequencies with those of indole as well as the predicted values from the ab initio calculations. Detailed analysis on the MATI spectra shows that the structure of the cation is somewhat different from that of this species in the neutral S₁ state.     

Mass-analyzed Threshold Ionization Spectroscopy of Rotamers of p-ethoxyphenol Cations and Configuration Effect

利用双色双光子质量分辨的阈值电离光谱技术,研究了对位乙氧基苯酚顺式和反式两种构型的离子态振动特性. 测得顺式和反式精确的绝热电离势分别为61565±5和61670±5 cm^-1. 与对位甲氧基苯酚实验结果比较,顺式和反式的测得的绝热电离势分别降低了645和643 cm^-1. 从所得到的两种构型的高分辨离子态光谱中,可知顺式和反式不同构型对苯环平面的振动影响很小,而低频率的C-OC₂H₅弯曲振动在两种构型中都很活跃.     

Pyridin type complexes of transition-metalhalides

A large number of Co-picoline-chlorides were prepared from different reaction media by changing the Co: picoline molar ratio.A new solid-gas phase method is described to prepare ternary mixed Co-picoline complexes containing different picolines.According to the thermal and spectral investigations the ligand chemisorption from the vapour phase depends on the stability of the solid complex and the complex formation ability of the ligand in the gas phase.

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Zusammenfassung In verschiedenen Reaktionsmedien wurden unter Änderung des Co: Pikolin Verhältnisses eine große Anzahl verschiedener C-Pikolinchloride hergestellt.Es wird eine neue Fest-Gas-Phasenmethode zur Herstellung ternärer Co-Pikolinmischkomplexe mit verschiedenen Pikolinen beschrieben.Entsprechend den thermischen und spektralen Untersuchungen hängt die Chemisorption der Liganden aus der Dampfphase von der Stabilität des festen Komplexes und vom Komplexbildungsvermögen des Liganden in der Gasphase ab.

     

Mass analyzed threshold ionization spectroscopy of 5-methylindole and 3-methylindole cations and the methyl substitution effect

The vibrationally resolved mass analyzed threshold ionization spectra of jetcooled 5-methylindole (5MI) and 3-methylindole (3MI) have been recorded by ionizing via various vibronic levels of each species. The adiabatic ionization energies (IEs) of 5MI and 3MI are determined to be 61,696+/-5 and 60,679+/-5 cm(-1), which are less than that of indole by 895 and 1912 cm(-1), respectively. Comparing these data with those of 1-methylindole and indole suggests that the methyl substitution on the pyrrole part leads to a greater redshift in the IE than on the benzene part. These experimental findings are well supported by the theoretical calculations. Analysis on these new data shows that many active vibrations of the 5MI cation are related to the CH(3) torsion and in-plane ring bending vibrations. In contrast, the observed vibrational bands of the 3MI cation are very weak due to unfavorable Franck-Condon transition.     

Mass-analyzed threshold ionization spectroscopy of deuterium-substituted isotopomers of o-fluoroaniline and m-fluoroaniline cations

We applied the resonant two-photon ionization and mass-analyzed threshold ionization techniques to record the vibronic and cation spectra of deuterium-substituted isotopomers of o-fluoroaniline (OFA) and m-fluoroaniline (MFA). The origins of the S₁ ← S₀ electronic transitions and adiabatic ionization energies of these isotopomers were precisely determined.     

EPR investigation and thermal study of yA<Subscript>2</Subscript>O-(1-<Emphasis Type="Italic">y</Emphasis>)[0.25(WO<Subscript>3</Subscript>)<Subscript>2</Subscript>-0.75(P<Subscript>2</Subscript>O<Subscript>5</Subscript>)] (A=Li,Na) glasses

Summary Glasses belonging to the series yA₂O-(1-y)[0.25(WO₃)_2-0.75P₂O₅] (y=0.10-0.60) are elaborated. DTA experiments reveal that the glass-network of the glasses are broken with increasing of modifier content. EPR spectra show the presence of two signals due to W⁵⁺ and Mo⁵⁺, as impuritie. The intensity of these EPR centres decreases when the concentration of A₂O increases. The variation of T_g upon the modifier content is ascribed to structural changes occurring in the matrix of these glasses.     

Pyridine-type complexes of transition-metal halides. III: Structural and thermal relationships among the cobalt(II) complexes with halide ions and 2-, 3-, and 4-Methylpyridine,the crystal structure of dibromotetrakis (3-methylpyridine)cobalt(II)

The correlation between structure and thermal properties of halogeno methylpyridine cobalt(II) is described. The ternary mixed tetrakis-derivatives and the tetrahedral bis-complexes of cobalt(II) chlorides and bromides formed with picolines are structurally very similar to the cadmium(II) and nickel(II) analogues, the iodides are somewhat different, however. On the basis of the characteristic correlation between the densities calculated from powder diffraction data and the molecular weights, the densities of a few thermal intermediates, which have not yet been prepared, are predicted. The square bipyramidal structure of dibromotetrakis(3-methylpyridine)cobalt(II) is described, and the deformation of the octahedra is discussed in detail. Structural study was extended by molecular mechanics (MM+ and MMX) and molecular orbital (SINDO1) calculations.     

Vibrational spectra of hexamethylcyclodisilazane

The synthesis and ring cleavage reactions of 2-alkyl-2-trimethylsilylmethyl-1.3-dithianes are described. The cleavage lead to 2-alkylthio-1-vinylsilanes and, via silicon migration, to 2-[3-alkylthio-3-(trimethylsilyl)propylthio]-1-alkenes.     

Chemical durability of MoO<Subscript>3</Subscript>-P<Subscript>2</Subscript>O<Subscript>5</Subscript> and K<Subscript>2</Subscript>O-MoO<Subscript>3</Subscript>-P<Subscript>2</Subscript>O<Subscript>5</Subscript> glasses

Thermal and chemical durability studies of the phosphate glasses belonging to the binary MoO₃-P₂O₅ and the ternary K₂O-MoO₃-P₂O₅ systems are reported. The chemical resistant attack tests carried out on the free alkaline MoO₃-P₂O₅ glasses show that the glass associated with the P/Mo ratio 2 has the high chemical durability. It shows also a high glass transition temperature value. The above findings are interpreted in terms of the cross-link density of the glasses and the strength of the M-O bonds (M=P, Mo). The influence of K₂O addition on the properties (density, T _g, durability) of this binary high water resistant glass is studied. It is found that the chemical durability along with the other physical properties are reduced by the incroporation of K₂O in the glass matrix. The results were explained by assuming the formation of non-bridging oxygens and weak bonds. The mechanism of the dissolution of these glasses is proposed.