Structures of some fluorinated benzenes determined by <i>ab initio</i> computation

Abstract

Abstract The structures of fluorobenzene, 1,3‐difluorobenzene, 1,3,5‐trifluorobenzene, 1,2,3‐trifluorobenzene, pentafluorobenzene, and hexafluorobenzene have been determined by the ab initio gradient method with a 4‐21 basis set. Approximate corrections have been developed to yield r e and r 0 structures so that comparison can be made with the available experimental information. The CF bond distance decreases in a uniform manner with increasing fluorination of the ring, either on adjacent or on meta sites. The ring structure also shows systematic deformation, with a decrease of about 0.01 Å in the CC bond length adjacent to the point of substitution and an increase of about 2.5˚ in the ring angle at the substitution site in those cases where the requirement of ring closure permits.