A Crystalline 2,3-exo-Disyndiotactic Dicyclopentadiene Tetramer

Cycloolefin oligomers and polymers have attracted attention for functional materials, but they are rarely seen in the crystalline state. A new crystalline cycloolefin dicyclopentadiene tetramer, having a 2,3-exo-disyndiotactic structure, is presented. By combining global optimization techniques based on configurational sampling in generalized statistical ensembles, with very high quality synchrotron X-ray diffraction data, the molecular mass of the crystallizing oligomer was first singled out, and its structure was then determined with a high degree of accuracy. The original procedures and methods developed for this particular case can be considered a suitable reference to tackle the difficult characterization problems posed by the crystalline powders of organic materials in general.