Structure of cyclobutanone

The microwave spectra of the ¹⁸O and the α,α,α',α'-tetradeuterated isotopic species of cyclobutanone have been investigated. Structural parameters determined are r _CO = 1.204 ± 0.006 Å, r _CHα = 1.099 ± 0.003 Å, ∠ H_αCH_α = 109.2 ± 1° with the methylene group tilted toward the carbonyl group by 4.6 ± 0.8°.