Single crystal software refinement

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. 

Crystals of 1-6 prepared as above were employed for the determination of molecular structure by single crystal X-ray diffraction. The relevant details of the crystal structures of the co-crystals are listed in Table l.f The intensity data were collected on a SMART system, Siemens, equipped with a CCD area detector,13 using Mo-Koc radiation. The structures were solved and refined using SHELXTL14 software. The refinements were uncomplicated and converged to good R-factors as... 

Compared to powder diffraction software, single crystal refinement programs are currently more advanced for routine structure refinement (Table 17.25). Compared to existing Rietveld software, it can be less time consuming to use a... 

Table 17.25 Available single crystal refinement and structure building software.

Improvements in hardware have been accompanied by enhancements to software that facilitate the refinement of even more complex strnctures. Techniques that have been developed for powder diffraction and protein crystallography can now be applied routinely to single-crystal analysis and vice versa. For single-crystal studies, this has led to more reliable refinements of weak, low-resolution datasets that are unavoidable when, as is often the case in supramolecular chemistry, only microscopic crystals are available. 

Single-crystal X-ray diffraction is the most useful experimental technique available for the determination of the three-dimensional crystal arrangement. Improvements in automated data collection methods on computer-controlled diffractometers and the development of more-robust refinement software has led to structure solution becoming almost routine. Over the past 10 years the total number of structures stored in the Cambridge Crystallographic Database (often referred to as the Cambridge Structural... 

All samples were single phase without detectable impurities. The crystal structure was refined by the Rietveld method (Rietveld, 1959) from X-ray powder diffraction data using GSAS software package (Larson Von Dreele, 1994). 

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