Gary A. Downing, David D. MacNicol and Christopher S. Frampton
In its stoichiometric 1:1 clathrate with acetone, studied by X-ray diffraction at 123 K, the title host molecule possesses a unique abbbabbb conformation with six side-chain units anti-parallel to the other two; the guest acetone’s conformation exhibits non-crystallographic C2 symmetry, and the observed lowering in symmetry from C2v in the vapour is accompanied by a significant opening of the guest’s C–C–C angle, in accord with a key theoretical prediction in the literature (J. Chem. Phys., 1993, 98, 2754).