Refinement of obverse/reverse twins.

Two examples of structures of obverse/reverse twins are presented. Example (1) is the structure of 2,2,4,4,6,6-hexa-tert-butylcyclotrisiloxane. It crystallizes in R3 macro c. Example (2) is the structure of [[Li(Me(3)Si)(3)CAlF(3)(thf)](3)LiF(thf)], tris[lithium tetrahydrofuran (trimethylsilyl)methyltrifluoroaluminate]lithium fluoride tetrahydrofuran. It crystallizes in R3. Additional to the obverse/reverse twinning this structure shows merohedral twinning. It will be shown how these two structures can be refined with the SHELXL program.