1,3‐Dihydro‐1‐hydroxy‐3‐morpholin‐4‐yl‐2,1‐benzoxaborole: product of the reaction of o‐formylphenylboronic acid with morpholine

o‐Formylphenylboronic acid reacts with morpholine to form 1,3‐dihydro‐1‐hydroxy‐3‐morpholin‐4‐yl‐2,1‐benzoxaborole. The typical hydrogen‐bonded dimer motif with a planar benzoxaborole fragment has been obtained in the solid state. Copyright © 2005 John Wiley & Sons, Ltd.     

Conformational analysis of 4-(2′-furyl)-2-(methylamino)pyrimidine

Conformational transformations of the title compound 1 were studied using high-resolution ¹H-nmr techniques, semi-empirical PM3 calculations and molecular dynamics. The unfused furan-pyrimidine ring system of 1 predominantly exists in an s-trans conformation in solution and the considerable sp² character of the C2?amino bond results in the hindered rotation which is observed on the nmr time scale.     

Twisted Hochschild Homology of Quantum Hyperplanes*

The twisted Hochschild homology groups of generic quantum hyperplanes are calculated using the Koszul resolution. For the example of the two-dimensional quantum plane also the twisted cyclic homology groups are determined. *Partially supported by Polish State Committee for Scientific Research (KBN) under grant 2 P03B 022 25     

Anomalies in low-temperature lattice parameters of ErFeO3 and ErAlO3 single crystals: correlation with magnetic properties

The paper presents the results of an experimental study of thermal expansion of isostructural orthorhombic ErFeO₃ and ErAlO₃ single crystals. Changes of lattice parameters have been investigated by X-ray measurements in the 10-300 K temperature range. Above ∼150 K, experimental results correspond well to the phonon mechanism. At low temperatures distinct anisotropic anomalies were observed in both compounds; and a correlation with the magnetic properties of the relevant ions is noted.     

Substituent effect on the excess Gibbs energy of saturated solutions of phenols

Solubility and vapour-pressure data have been measured and used to evaluate excess Gibbs energies G_N^E for several phenols along the solid-liquid equilibrium curve. The effect of the structure of the solute molecule on the extremum G_N^E value is discussed.     

Geometry of crystal structure with defects. II. Non-Euclidean picture

The following point of view is geometrically formulated and its consequences examined: the lattice of a crystalline body with a continuous distribution of dislocations can be locally described as an ideal lattice in non-Euclidean space. The types of distribution of dislocations are described by the classification of three-dimensional real Lie algebras. The influence of point defects and the elastic deformation field on the geometry of the material structure of a crystalline body with dislocations is examined. The case where a crystal with dislocations reacts as a body with internal rotational degrees of freedom is discussed.     

CNDO calculations of diamagnetic shielding in molecules

An approximate procedure for the calculation of diamagnetic shielding in molecules is presented. The method proposed is based on the ‘complete neglect of differential overlap’ (CNDO) molecular wave functions and is formulated according to the zero differential overlap (ZDO) approximation. The results obtained with several CNDO-type wave functions for diatomic and polyatomic molecules are in very good agreement with non-empirical SCF calculations. The ¹⁴N diamagnetic shielding constants in several molecules were computed and some approximations usually adopted in the interpretation of ¹⁴N chemical shifts are critically discussed. It was shown that in some cases the observed ¹⁴N chemical shifts cannot be interpreted solely in terms of the paramagnetic contribution to the shielding constant.