Photodimerisation of 2-benzyl-5-p-bromobenzylidenecyclopentanone, a crystal–crystal transformation: X-ray study of the dimer

Abstract

2-Benzyl-5-p-bromobenzylidenecyclopentanone photodimerises in the crystalline state, yielding directly a crystalline dimer. The dimer crystallises in the orthorhombic space group Pbca with Z= 4 in a unit cell of dimensions: a= 10·27, b= 8·98, and c= 32·96 A. The X-ray crystal structure was solved from diffractometer data by the heavy-atom method with conventional Patterson and fourier techniques and refined by least-squares methods to R 0·134 for 1674 independent reflections.