A deconvolutional method for preprocessing powder diffraction data has been improved. The cumulants of instrumental aberration functions of Bragg-Brentano (Parrish) diffractometer calculated up to the fourth order are presented. The treatments of axial-divergence aberration and the effective spectroscopic profile of the source X-ray have been simplified from those used in previous methods. The current method has been applied to powder diffraction data collected with a Cu-target X-ray tube, used over 20 years, and a Ni-foil Kβ filter.

The crystal structure of trimethylarsine oxide dihydrate, (CH3)3AsO⋅2H2O, (TMAO dihydrate) has been solved using parallel tempering with the FOX software package and refined using synchrotron powder diffraction data obtained from beamline 08B1-1 at the Canadian Light Source. Rietveld refinement, performed with the software package GSASII, yielded orthorhombic lattice parameters of a = 13.3937(4) Å, b = 9.53025(30) Å, and c = 11.5951(3) Å (Z = 8, space group Pbca). The Rietveld refined structure was compared with density functional theory calculations performed with VASP and shows reasonable agreement. Arsenic K-edge X-ray absorption spectroscopy analysis also revealed additional information on the electronic structure of the arsenic atom within the TMAO dihydrate structure.

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Commercial fluorometholone, CAS #426-13-1, crystallizes in the monoclinic space group P21 (#4) with a = 6.40648(2), b = 13.43260(5), c = 11.00060(8) Å, β = 92.8203(5)°, V = 945.517(5) Å3, and Z = 2. A reduced cell search in the Cambridge Structural Database yielded one previous structure determination, using single-crystal data at 292 K. In this work, the sample was ordered from the United States Pharmacopeial Convention (Lot # R032K0) and analyzed as-received. The room temperature (295 K) crystal structure was refined using synchrotron (λ = 0.412826 Å) powder diffraction data and optimized using density functional theory (DFT) techniques. Hydrogen positions were included as a part of the structure and were re-calculated during the refinement. The diffraction data were collected on beamline 11-BM at the Advanced Photon Source, Argonne National Laboratory, and the powder X-ray diffraction pattern of the compound has been submitted to ICDD® for inclusion in the Powder Diffraction File™. The agreement of the Rietveld-refined and DFT-optimized structures is excellent; the root-mean-square Cartesian displacement is 0.060 Å. In addition to the O–H⋯O hydrogen bonds observed by Park et al. (Park, Y. J., Lee, M. Y., and Cho, S. I. (1992). “Fluorometholone,” J. Korean Chem. Soc. 36, 812–817), C–H⋯O hydrogen bonds contribute to the crystal energy.

The crystal structure of pantoprazole sodium sesquihydrate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Pantoprazole sodium sesquihydrate crystallizes in space groupPbca(#61) witha= 33.4862(6),b= 17.29311(10),c= 13.55953(10) Å,V= 7852.06(14) Å3, andZ= 16. The crystal structure is characterized by layers parallel to thebc-plane. One layer contains the Na coordination spheres. The two independent sodium ions are trigonal bipyramidal and octahedral. The NaO3N2and NaO4N2coordination spheres share an edge to form pairs. The sodium bond valence sums are 1.17 and 1.15. The difluoromethyl groups are probably disordered. Two water molecules act as hydrogen bond donors to pyridine nitrogen atoms and sulfoxide oxygen atoms. The third water molecule participates in bifurcated hydrogen bonds, but one of its hydrogen atoms does not participate in hydrogen bonds. The powder pattern is included in the Powder Diffraction File™ as entry 00-065-1424.

The crystal structure of ipratropium bromide monohydrate has been solved and refined using synchrotron X-ray powder diffraction data and optimized using density functional techniques. Ipratropium bromide monohydrate crystallizes in the space group P21/c (#14) with a = 8.21420(7) Å, b = 10.54617(13) Å, c = 24.0761(39) Å, β = 99.9063(7) °, V = 2054.574(22) Å3, and Z = 4. Both hydrogen atoms of the water molecule act as donors to the bromide cation, forming a ring with the graph set R2,4(8). The hydroxyl group also acts as a donor to Br. Several C–H⋯Br hydrogen bonds are present. The water molecule acts as an acceptor in two C–H⋯O hydrogen bonds from methyl groups. The ketone acts as an acceptor in C–H⋯O hydrogen bonds from methyl groups, a methylene group, and a methyne group. The hydroxyl group acts as an acceptor in a C–H⋯O hydrogen bond from a phenyl carbon atom. The powder pattern is included in the Powder Diffraction File™ as entry 00-066-1611.

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