Stereochemistry of benzophenone derivatives: crystal and molecular structure of 3,3′-dibromobenzophenone

The structure of 3,3′-dibromobenzophenone has been reinvestigated using new three-dimensional data. Crystals of 3,3′-dibromobenzophenone are orthorhombic:a = 4·05,b = 11·74,c = 24·80 Å,Z = 4, space groupPbcn. The structure has been refined by three-dimensional methods, including anisotropic full-matrix least squares, to anR index 0·104. The conformation of isolated molecules of benzophenone,pp′-dimethoxy benzophenone and 3,3′-dibromobenzophenone have been calculated by semi-empirical methods, and the results are compared with those obtained from X-ray crystallographic investigations on these compounds. It has been found that the calculated geometries of isolated molecules of benzophenone and its derivatives are different from those observed in the crystal structures of these compounds.