4-CYANO-4'-[(4R)-4,5-EPOXYPENTYLOXY]BIPHENYL - A PSEUDOSYMMETRY PROBLEM SOLVED WITH SYNCHROTRON DATA

The title compound, -[(4R)-4,5-epoxypentyloxy]-4-biphenylcarbonitrile, C18H17NO2, crystallizes in space group P2(1) with two independent mol ecules of identical chirality. The molecules differ significantly only in the conformation of the substituent containing the epoxide ring. W ith the exception of this ring, the structure approximates closely to the centrosymmetric space group P2(1)/n, in which refinement can be ac hieved with the assumption of twofold disorder of orientation of the e poxide ring and a racemic material. The pseudosymmetry is resolved by a weak subset of h0l reflections (h + l = 2n), which are found to be s ignificant in a synchrotron data set. The two rings of the biphenyl un it are essentially coplanar, in contrast to most 4-cyano-4'-(alkyloxy) biphenyl compounds.