SHELXL

SHELXL is part of the SHELX program suite, a software package containing the following programs  

Stmcture solution by Patterson and classical direct methods. Structure solution not only for macromolecules. 

Structure refinement for very large structures (in principal identical with SHELXL, but the maximum number of allowed parameters is larger). 

This protein interface to SHELX is a collection of different routines to convert file formats, calculate electron density 

All these programs can be obtained free of charge from George Sheldrick for a multitude of operating systems (www.shelx.uni-ac.gwdg.de/SHELX) the only requirement is to fill out a registration form. 

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X-ray structural analysis. Suitable crystals of compound 14 were obtained from toluene/ether solutions. X-ray data were collected on a STOE-IPDS diffractometer using graphite monochromated Mo-Ka radiation. The structure was solved by direct methods (SHELXS-86)16 and refined by full-matrix-least-squares techniques against F2 (SHELXL-93).17 Crystal dimensions 0.3 0.2 0.1 mm, yellow-orange prisms, 3612 reflections measured, 3612 were independent of symmetry and 1624 were observed (I > 2ct(7)), R1 = 0.048, wR2 (all data) = 0.151, 295 parameters. 

Sheldrick, G.M. (1997) SHELXL-97, Program for Crystal Structure Refinement, University of Gottingen, Germany, Windows version by McArdle by National University of Ireland, Galway, Ireland. 

SHELXL [28] is the most commonly used structure refinement program. We have devised a strategy for addressing the refinement ... 

Sheldrick, G. M. (1997). SHELXL-97. A computer program for the Refinement of Crystal Structures. University of Gdttigen, Germany. 

After merging of the single zones, data sets of approx. 100-300 independent reflections can be obtained as described in chapter 2.5. In a first step a kinematical structure refinement should be performed using the program SHELXL [13]. The temperature factors for FAPPO were chosen as U = 0.06 for C, N and O as U = 0.10 for H atoms apart from H atoms situated at N with U = 0.12 A (Electron scattering factors [20]). To prevent the molecules from being distorted a refinement, where the whole molecule was kept rigid, was performed. This also improves the usually bad parameter/reflection ratio. In the case of modification I we obtained R-values of 31% (481 unique reflections with I > 2cr) for the 100 kV data and of 25% (385 unique reflections with I > 2a). The sparse 100 kV data of modification II was not analysed quantitatively. From 300 kV data we obtained an R-value of 23% (226 unique reflections with I > 2a). 

G.M. Sheldrick, SHELXL, Program for crystal structure refinement. University of Gottingen, Germany 1999. 

SHELXL (Sheldrick and Schneider, 1997) is often viewed as a refinement program for high-resolution data only. Although it undoubtedly offers features needed for that resolution regime (optimization of anisotropic temperature factors, occupancy refinement, full matrix least squares to obtain standard deviations from the inverse Hessian matrix, flexible definitions for NCS, easiness to describe partially... 

SHELXL-93 G. M. Sheldrick, Gottingen 1993. CRYLSQ Xtal 3.0 R. Olthof-Hazekamp in Reference Manual, S. R. Hall, J. M. Stewart, Eds., Lamb. Perth 1990. 

P. Muller, R. Herbst-Irmer, A. Spek, T. Schneider and M. Sawaya, Crystal Structure Refinement A Crvslallog rap her s Guide to SHELXL, Oxford University Press, Oxford, 2006. 

Crystal structure refinement a crystallographer s guide to SHELXL P. Muller, editor... 

Sheldrick G. M., SHELXL-93 A Program for the Refinement of Crystal Structures from Diffraction Data, University of Gottingen, Germany (1993). 

X-Ray Crystallography Determination of the unit cell and data collection were performed at room temperature on an Enraf-Nonius CAD4 diffractometer, using a graphite-monochromated Mo-Ka radiation (y = 0.71073 A). The structures were solved by direct methods using Siemens SHELXS-97 and refined by least-squares procedures on Fo with SHELXL-97 by minimizing the function w(Fo -Fc ), where Fo and Fc are the... 

There is a variety of software that can be used to process pseudo-single crystal experimental diffraction data represented in a form of individual structure factors or their squares (consult http //www.iucr.org and/or http //www.ccpl4.ac.uk). The most commonly used software products are SHELXS-90 and SHELXL-97 (author G.M. Sheldrick), which are distributed free for academic use (consult SHELX home page at http //shelx.uni-ac.gwdg.de/SHELX/index.html for details). Unless noted otherwise, processing of the individual structure factor data, direct phase determination, Patterson-, Fourier- and E-map calculations shown in this chapter were performed using WinCSD software, which is available from STOE Cie, Gmbh (http //www.stoe.com/products/index.htm). 

G. M. Sheldrick, Phase annealing in SHELXS-90 direct methods for larger structures, Acta Cryst. A46, 467 (1990) G. M. Sheldrick, SHELXL-97. University of Gottingen, Germany, (1997). See the footnote on page 515 on how to obtain the programs. 

The obtained model was refined by using SHELXL-97 to Rp = 25 %, which resulted in the coordinates listed in Table 6.36. Two oxygen atoms,... 

Table 6.36. Results of structure refinement (SHELXL-97) and the difference Fourier peaks...

The least squares refinement of this model using SHELXL-97 yields Rp = 42 % as shown in Table 6.39. All oxygen atoms and the isolated nitrogen atom look reasonable because their distances to the vanadium atoms are within acceptable limits. What is not shown in Table 6.39 is that the coordination polyhedra of V atoms make both chemical and physical sense vanadium oxide forms a layer, composed of VO5 pyramids and tetrahedral VO4, as illustrated in Figure 6.28. This layer is similar to layers known for... 

Le Bail or Pawley extracted list of intensities with single crystal software such as Shelxl or Crystals to perform early cycles of refinement to find missing atoms, and graphically examine the structure. This is also an area where it might be helpful to Armel Le Bail s Overlap program (listed in Table 17.16) to remove reflections that are excessively overlapped. 

Sheldrick G, Schneider T (1997) SHELXL high-resolution refinement. Methods Enzymol 277 319-343... 

General for 2 and 3 Three dimensional intensity data collected on a Bruker SMART CCD diffractometer at 293(2) K MoK, radiation (0.71073 A) reflections corrected for Lorentz and polarisation effects and absorption corrections applied using SADABS structures solved by direct method and successive Fourier synthesis (SHELXS-97 and SHELXL-97) hydrogen atoms placed in calculated positions with fixed isotropic thermal parameters R = [(ZAF)/(ZF )] wR = Z[w(F "-F,2)2]/Z[w(F 2)2]i ... 

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