Substituent-dependent formation of supramolecular aggregates of 6-hydroxy-trans-3-hexenoic acids in the solid state

The substituted 6-hydroxy-trans-3-hexenoic acids 2-4 have been prepared by a template coupling reaction between (butadiene)zirconocene, W(CO)(6), and cyclobutanone, cyclodecanone, or cyclododecanone, respectively, followed by hydrolytic/oxidative demetallation of the resulting metallacyclic zirconox ycarbene tungsten complexes. The hydroxyalkenoic acids 2-4 have been found to form two novel fundamental types of associated supramolecular structural arrays in the solid state through intermolecular hydrogen bonding, which h ave been characterized by X-ray diffraction analysis. The cyclobutanone-der ived compound 2 exhibits an infinitely extending sheet-like structure, whic h is composed of symmetrically alternating interconnected 12- and 36-member ed rings, each being constructed from the functional groups or frameworks o f four individual molecules of 2. In contrast, the cyclodecanone-derived co mpound 3 adopts a ribbon-type structure composed of C-2-symmetrically arran ged symmetry-equivalent 15-membered rings, each containing the functionalit ies from three individual molecules of 2. On the basis of scanning force mi croscopy studies, the cyclododecanone-derived compound 4 would appear to ha ve a similar structure in the solid state. The structural features of the m olecular assemblies that are formed by intermolecular hydrogen bonding of c ompounds 2-4 in the solid state are selectively controlled by the size and favoured conformations of the spiro-anellated carbocyclic rings at C6 of th e 6-hydroxy-trans-3-hexenoic acid carbon chain.