A Rietveld refinement using neutron powder diffraction data of a fully deuterated topaz, Al₂SiO₄(OD)₂

The structure of topaz-OD, dialuminium orthosilicate di­hydro­xide, Al₂SiO₄(OD)₂, was refined in the space group Pbnm by Rietveld analysis of constant wavelength neutron powder diffraction data. Two non-equivalent half-occupied deuterium positions were located. Each D atom is characterized by an irregular trifurcated hydrogen-bond geometry. The refined hydrogen-bond distances are in the ranges 2.038 (5)-2.281 (6) and 2.280 (5)-2.524 (6) Å for the two D atoms. Hydro­gen-bond angles range from 83.6 (4) to 151.9 (4)°. Results indicate that it is feasible to characterize the hydrogen bonding in small-volume samples (25 mg) synthesized at high pressure and temperature.

3,4,5-Trimethoxy­phen­yl 4-bromo-7-meth­oxy-1,3-benzodioxole-5-carboxyl­ate

The title compound, C₁₈H₁₇BrO₈, was synthesized in an anhydrous medium at 293 K. The dihedral angle between the two benzene rings is 38.8 (2)°.

(1R,2R,2′S)-2-(4-Methyl­phenyl­sulfonamido)-1-(pyrrolidine-2′-carboxamido)cyclo­hexa­ne

The title compound, C₁₈H₂₇N₃O₃S, is an organocatalyst prepared from (1R,2R)-cyclo­hexa­ne-1,2-diamine. There are bifurcated N—H...N/O intra­molecular hydrogen bonds and N—H...O and C—H...O inter­molecular inter­actions.