Structural Comparison of Indene and Indenyl Using Electron Diffraction

Abstract
The structure of indene, C9H8, was studied by electron diffraction for the sake of a comparison to the results previously obtained for indenyl. The mean C–C bond distance is the same (1.415 ű0.01) for both molecules. The C–C bond distance range of indene (0.17 ű0.02), however, is considerably larger than in the radical (0.09 Å). A structure is proposed for indene which, in view of the large number of independent parameters, must be considered as a nonunique solution of the electron diffraction pattern.