Feb 032012
 
Methyl 6-amino-6-oxohexanoate & 3-Methoxy-3-oxopropanaminium chloride (T. Gruber, C. J. Schofield and A. L. Thompson)

Acta Cryst. (2012), E68, o593-o594.    [ doi:10.1107/S1600536812003303 ]

The title compound, C7H13NO3, adopts an approximately planar conformation. The torsion angles in the aliphatic chain between the carbonyl group C atoms range from 172.97 (14) to 179.38 (14)° and the r.m.s. deviation of all non-H atoms is 0.059 Å. … Read the rest

Sep 132011
 
CRYSTALS Enhancements:  Absolute Structure Determination (A. L. Thompson and D. J. Watkin)

J. Appl. Cryst.  (2011), 44, 1017-1022.    [ doi:10.1107/S0021889811034066 ]

A summary of the features for investigating absolute structure available in the crystallographic refinement program CRYSTALS is presented, together with the results of analyses of 150 light-atom structures collected with molybdenum radiation carried out with these tools. The results confirm that the Flack and Hooft … Read the rest

Feb 152011
 
Chiral Selection in the Formation of Borates from Racemic Binaphthols and Related Diols (J. A. Raskatov, J. M. Brown and A. L. Thompson)

CrystEngComm (2011), 13(8) 2923-2929.    [ doi:10.1039/c0ce00709a ]

A series of racemic or stereochemically labile chiral borate anions based on the 2,20-biphenol motif was
investigated. All borates were homochiral in the solid state, although in some cases the heterochiral
diastereomers were computed to be thermodynamically preferred (DFT). The crystallographic
preference for the homochiral diastereomer was … Read the rest

Dec 072010
 
Practical Applications of Averages and Differences of Friedel Opposites (H. D. Flack, M. Sadki, A. L. Thompson and D. J. Watkin)

Acta Cryst. (2011), A67, 21-34.    [ doi:10.1107/S010876731004287X ]

The practical use of the average and difference intensities of Friedel opposites at different stages of structure analysis has been investigated. It is shown how these values may be properly and practically used at the stage of space-group determination. At the stage of least-squares refinement, … Read the rest

Nov 272010
 

J. Appl. Cryst. (2011), 44, 52-59.    [ doi:10.1107/S0021889810042470 ]

One of the requirements for the next generation of small-molecule crystallographers is a mathematical programming infrastructure. It should provide a modelling design process, where the model formulation is kept separate from the optimization process to provide gains in reliability, scalability and extensibility, enabling the application … Read the rest

Jul 132010
 

Cryst. Rev. (2010), 16(3), 197-230.    [ doi:10.1080/08893110903483246 ]

X-ray single crystal structure analysis has become a gold standard for the determination of molecular geometry. The reliability of the technique is a triumph for science and technology working together. The uniqueness of well-crystalline material intrigued early natural philosophers, and their examinations, followed by the discovery … Read the rest

Jun 292010
 
CRYSTALS Enhancements: Dealing with Hydrogen Atoms in Refinement (R. I. Cooper, A. L. Thompson and D. J. Watkin)

J. Appl. Cryst. (2010), 43, 1100-1107.    [ doi:10.1107/S0021889810025598 ]

Because they scatter X-rays weakly, H atoms are often abused or neglected during structure refinement. The reasons why the H atoms should be included in the refinement and some of the consequences of mistreatment are discussed along with selected real examples demonstrating some of the … Read the rest

Apr 152010
 

Cryst. Rev. (2010), 16(2), 133-144.    [ doi:10.1080/08893110903483238 ]

Recent developments in crystallographic error analysis are described. This report provides an introduction to more-formal work, originally published in Ref. (Haestier, J., J. Appl. Cryst. 2009, 42, 798). Prior to the main discussion, a brief overview of the normal distribution and error-propagation is … Read the rest

Nov 182009
 

Acta Cryst. (2009), C65, o635-o638.    [ doi:10.1107/S0108270109046952 ]

The unusual methylene aziridine 6-tert-butyl-3-oxa-2-thia-1-azabicyclo[5.1.0]oct-6-ene 2,2-dioxide, C9H15NO3S, was found to crystallize with two molecules in the asymmetric unit. The structure was solved in both the approximately orthogonal and the oblique settings of space group No. 14, viz. Read the rest

Oct 302009
 
Synthesis and Structural Studies of Gallium(III) and Indium(III) Complexes of 2-acetylpyridine Thiosemicarbazones (J. Chan, A. L. Thompson, M. W. Jones, J. M. Peach)

Inorg. Chim. Acta  (2010), 363(6), 1140-1149.    [ doi:10.1016/j.ica.2009.10.020 ]

Four 2-acetylpyridine 4N-alkyl thiosemicarbazones, and their Ga(III) and In(III) complexes have been prepared and characterised by fluorescence, UV–Vis, IR, 1H and 13C NMR spectroscopy, mass spectrometry and X-ray crystallographic analysis. Comparison of the crystal structures gave an insight into the nature of … Read the rest