The molecular structure of acetylacetone as studied by gas-phase electron diffraction

Abstract The molecular structure of the enol form of gaseous acetylacetone has been determined from electron diffraction data. The molecular skeleton is planar but it is not symmetric. The bond distances in the ring are r g (CO) = 1.243 ± 0.002 A, r g (CO) = 1.319 ± 0.003 A, r g (CC) = 1.382 ± 0.007, r g (CC) = 1.430 ± 0.008 A, r g (OH) = 1.049 ± 0.015 A and r g (O⋯O) = 2.512 ± 0.008 A. The hydrogen atom of the internal hydrogen bond lies 0.45 ± 0.08 A out of the molecular plane with the OHO angle of 137 ± 7°.