The meta-dinitrobenzene crystal structure has been determined at five temperatures in the 100-300 K temperature range. The thermal expansion coefficients have been calculated from the temperature variation of the lattice parameters. Rigid-body motion analysis with allowance for large-amplitude internal motions provided the T, L and S tensors' values at the temperatures studied and was used to characterize the torsional motion of two nitro groups in the molecule. Frequencies of the translational and librational modes and of the torsional modes of the nitro groups have been compared with the wave numbers at the maximum of bands in the low-frequency Raman and IR spectra. Ab initio calculations were performed in order to assess the contribution from large-amplitude internal motions to the static first-order hyperpolarizability of the m-dinitrobenzene molecule.

Crystal structures of two polymorphic forms of m-nitrophenol have been determined at several temperatures between 95 to 350 K. The thermal expansion tensor and the rigid-body translation and libration tensors have been calculated for both polymorphs at different temperatures. Quantum chemical calculations of interactions for molecular clusters that modeled two polymorphic crystal structures have been performed. The comparison of molecular interaction energies and dynamics in polymorphs has been considered in terms of the large hysteresis of the metastable phase occurrence. Evidence of the reconstructive transition is reported. The molecular mechanism of the transition in one direction is controlled by thermally induced molecular librations coupled with internal torsions of nitro groups. The torsional vibrations of nitro groups are damped in the high-temperature phase making the reverse transformation impossible due to the cooling.

No abstract

Reaction of commercially available trialkyl phosphites with N‐phthalylamino acids gave mixtures of seven products, whereas the same reaction carried out with pure triethyl phosphite yielded only the desired 2‐(N‐phthalylamino)‐1‐oxoalkanephosphonates. These compounds underwent rearrangement to the same types of products that were obtained with the commercial phosphites. This latter series of reactions was promoted by the presence of dialkyl phosphites. © 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:232–239, 2000