Spectroscopic Evidence for Pseudorotation of Seven-Membered Chalcogen Rings in Solution [1]

The 77Se NMR spectrum of 1,2-Se2S5 exhibits one singlet at 1077.3 ppm indicating pseudorotation in solution; the same conclusion is reached from the solution Raman spectrum of S7 showing characteristic line broadening compared to the solid state spectrum

Spektralreines Bis(phthalocyaninato)protactinium(IV) / Spectroscopically Pure Bis(phthalocyaninato)protactinium(IV)

Spectroscopically pure PaPc2 has been prepared by reaction between PaI4 · 4 CH3CN and o-phthalic acid dinitrile in 1-chloronaphthalene followed by sublimation at 5 · 10-3 Pa in a temperature profile with three clearly defined zones (520 °C/350 °C/room temperature). This procedure gives a product almost completely free of H2Pc impurity which is known to have been present in previously reported complexes of the type AnPc2. Thus, the trace of H2Pc in the substance could only be detected by derivative spectroscopy. X-ray powder diffraction shows the compound to be isostructural with ThPc2 and UPc2. The ligand spectrum is typical of AnPc2 complexes, f-f Bands observed in a solid state spectrum provide additional proof that the compound is PaIV Pc2.

Vibrational Spectra of Trifluorothiolacetic Acid: Hydrogen Bonding and Conformational Effects

Infrared spectra were obtained for trifluorothiolacetic acid in the vapor, liquid, and solid states, and the Raman spectrum of the liquid was obtained. The spectra have been interpreted in terms of two rotational isomers being present in the liquid state, with the hydrogen atom being either eclipsed with or trans to the oxygen. The solid state spectrum was interpreted to be due to a hydrogen-bonded dimer. The absence of the hydrogen bonding in the liquid indicates a hydrogen bond energy of only a few hundred calories per mole. A vibrational assignment is proposed.