C-H center dot center dot center dot F Hydrogen Bonds in Solid Solutions of Benzoic Acid and 4-Fluorobenzoic acid

Solid solutions (SS) of benzoic acid (BA) and 4-fluorobenzoic acid (4FBA) are monitored with respect to increasing fluorine content. All 10 SS studied take a crystal structure that is different from the crystal structures of either BA or 4FBA and retain structural uniformity over a wide range of composition. Adoption of a crystal structure different from either of the parent structure types is a unique observation in the context of SS. It implies the influence of directional interactions in the formation of the SS; this idea is strengthened by the observations made in this study. All the structural and interaction parameters monitored follow trends with respect to fluorine content. There is indication of the effect of C-H center dot center dot center dot F hydrogen bonds in the structures