Cyclopentanone and cyclobutanone.

Crystals of cyclopentanone, C(5)H(8)O, and cyclobutanone, C(4)H(6)O, have been grown in situ on a diffractometer. The two compounds are isostructural and contain two crystallographically independent molecules. Molecules sitting across twofold axes form antiparallel dipole-dipole dimers, while other molecules in general positions are linked together into ribbons by pairs of C-H...O interactions.