Crystal engineering and chloro-methyl interchange - a CSD analysis

A search method for investigating the extent to which chloro-methyl interch ange is exhibited by crystal structures deposited with the Cambridge Crysta llographic Database is presented. Using the October 1998 release with 190,3 07 data entries, 105 pairs were identified for which there was a common mol ecular framework, differing only in the presence of a chloro or methyl grou p. Approximately 30% appear to demonstrate isotructural packing arrangement s. Two examples within the database that were found nor to show CI-Me inter change were subsequently examined from the viewpoint of structural mimicry and the formation of mixed crystals.