Simple Disorder - Sorbose

Simple disorder using SHELXL: sorbose

Note: This tutorial uses older programs: shelxs, shelxl97, and shelxtl XP.
This tutorial is intended to be an easy introduction to dealing with disorder using SHELXL. In spite of what you may have been told, disorder is not necessarily difficult to deal with, you simply have to know what to do. The structure in question is sorbose, a monosaccharide. Before we get started, it may help to know exactly what we are going to do. The picture below is an ellipsoid plot of sorbose. If you roll your mouse over it, you should see that the CH₂OH group on the right hand side shifts to a new orientation. The hydroxymethyl group in sorbose is disordered. In SHELXL, disorder is handled by splitting the atom list into PARTs. 'PART 0' is the non-disordered stuff, 'PART 1' is the major component, and 'PART 2' is the minor component. This tutorial will show you how to do this.

We start this tutorial with a Cu-Kα X-ray dataset ('.hkl' file), collected on a Bruker-Nonius X8 Proteum diffractometer, and a SHELXS instructions ('.ins') file, created by XPREP. If you are unsure of what these things are, then you should read the first tutorial in this series, here: A routine structure determination using SHELXTL: sucrose.

The two files can be downloaded here:

The important stuff in this first disorder tutorial is in 'Part 3: Refine the structure'. Structure solution and initial editing are really not much different than for the sucrose example. They are included here just to show that no magic is needed to deal with disorder.