title: Comment on "Single-crystal X-ray structure of 1,3-dimethylcyclobutadiene by confinement in a crystalline matrix".
abstract: Legrand et al. (Reports, 16 July 2010, p. 299) reported the experimental observation of square-planar and rectangular-bent geometries of 1,3-dimethylcyclobutadiene (Me(2)CBD) confined within a crystalline matrix. However, we found no evidence for the Me(2)CBD formation. We argue that the experimental x-ray density data are better attributed to the bicyclic β-lactone intermediate where carbon dioxide is covalently bound to cyclobutadiene.
authors.affiliation: Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306, USA. alabugin@chem.fsu.edu
authors.forename: Igor V
authors.initials: IV
authors.lastname: Alabugin
authors.forename: Brian
authors.initials: B
authors.lastname: Gold
authors.forename: Michael
authors.initials: M
authors.lastname: Shatruk
authors.forename: Kirill
authors.initials: K
authors.lastname: Kovnir