Crystal structure and nuclear magnetic resonance spectra of a 1 : 1 complex of benz[a]anthracene and pyromellitic dianhydride (benzene-1,2,4,5-tetracarboxylic dianhydride)

Abstract

The crystal structure of a 1 : 1 complex of benz[a]anthracene(BA) and pyromellitic dianhydride(PMDA) has been determined by direct methods from diffractometer data and refined to R 0.0825 for 1 354 reflections. Crystals are orthorhombic with a= 11.63(1), b= 20.84(2), c= 7.089(6)Å, Z= 4, space group Pna2₁. C–C Bond lengths in BA vary from 1.321 (11) to 1.482(11)Å, but are as expected in PMDA. An n.m.r. study of the complex in solution in 1,2-dichloroethane at 33.5 °C gave an association constant (K) of 3.4 mol kg^–1, but gave no evidence of the presence of complexes with stoicheiometries other than 1 : 1.