STRUCTURAL LIBRARY OF COMMONLY DISORDERED COUNTER IONS AND INCLUDED MOLECULES. ESTABLISHMENT OF SELECTION CRITERIA AND METHODOLOGY. Richard J. Staples, University of Idaho and Joseph H. Reibenspies, Texas A&M University.

Disordered counter ions and/or included molecules often pose a difficult task to model in crystal structure elucidation. The disordered molecules are often modeled by restraining their molecular dimensions to known or estimated parameters or by least -squares fitting to structural models taken from the literature or molecular modeling programs. Unfortunately, there appears to be no universally accepted molecular parameters for these common molecules. The first purpose of this work is to establish an ordered set of selection criteria that can be utilized in database searches for the recovery of these molecules. The second purpose is to develop a useful format for rapid incorporation of these results in crystallographic programs. Presentation of these criteria and examples of their use will be presented.