Racemic mimics. Part 1. Nickel coordination compounds.

To date there are very few examples of crystallographically well-documented racemic mimics. The original discovery of this class of crystals occurred at a time when crystallography was in its infancy, data collection and processing were tedious and limited by X-ray equipment, and computing power was indeed limited. Therefore, this interesting class of crystalline molecules, potentially having useful biological uses, is today one of those scientific orphans largely ignored in the crystallographic realm. As proof of this, to date, you cannot systematically search for this class in databases. Thus, for the time being, there are few satisfactory examples of high-quality crystal structures of both members of such pairs which have been highlighted in the literature. Finally, being largely undocumented, there are no useful clues to guide you as to how to guess the classes of compounds likely to produce such pairs. The question then is, how do we go about searching for potential cases of such crystallization modes using information already in print? Herein, we provide some suggestions we believe are useful, and to the extent possible with such data, to illustrate the possibilities offered by such an approach.