UORO-1,2,7,8-TETRAKIS(TRIFLUOROMETHYL)PHENANTHRENE AND LUORO-1,2,5,6-TETRAKIS(TRIFLUOROMETHYL)-ANTHRACENE

A photocyclization reaction produces two isomers of C18H2F16. Crystal structures show the major product to be oro-1,2,7,8-tetrakis(trifluoro methyl)phenanthrene, (1), and the minor product to be uoro-1,2,5,6-tet rakis(trifluoromethyl)-anthracene, (2). The phenanthrene skeleton in ( 1) is distorted from planarity by steric interaction between the 4- an d 7-F atoms. Compound (2) is centered on an inversion center; the anth racene skeleton is nearly planar, with the trifluoromethyl atoms displ aced on either side of the molecular plane.