X-ray diffraction study of the crystal structure of the π-molecular compound pyrene···pyromellitic dianhydride at 19 K

Abstract

The crystal structure of the pyrene···pyromellitic dianhydride (PMDA) π-molecular compound [(C _(16)H_(10):C_(10)-H_2O_6); PYRPMA] has been refined from intensities measured at 19 K using the low-temperature accessory designed by Samson, Goldish & Dick [J. Appl. Cryst. (1980), 13, 425-432] for a four-circle diffractometer. Earlier results for the ordered structure [Herbstein & Snyman (1969). Philos. Trans. R. Soc. London Ser. A, 264, 635-666] are confirmed and extended; at 19 K, a = 13.664 (3), b = 9.281 (2), c = 14.420 (3) Å, β = 91.80 (2)°, space group P2_1/n = 4, with two sets of pyrenes at independent centres of symmetry and the four PMDAs at general positions. The geometrical structures of the two components are in good agreement with quantum mechanical calculations. Analyses of thermal motion and packing show that one set of pyrenes is more tightly packed than the other; the principal interactions in the crystal are π-π* plane-to-plane interactions between pyrene and PMDA and >CH···O=C<, between pyrene and PMDA, and between PMDAs.

Additional Information

© 1994 International Union of Crystallography. Received 2 August 1993; accepted 21 October 1993. This work has been supported by the Fund of the Vice President for Research and the Fund for Promotion of Research at Technion, by the CSIR (Pretoria) and by a number of NIH grants. We are grateful to Professor Verner Schomaker (Caltech) for help with THMA11, to Dr M. Kapon (Chemistry, Technion) for help with computing and to Dr Max Dobler (ETH, Zurich) for a copy of MacMoMo. The referees have also been very helpful.

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