title: The bisketene radical cation and its formation by oxidative ring-opening of cyclobutenedione.
abstract: Parent cyclobutenedione 1 was photolyzed and ionized in an Ar matrix at 10K. The bisketene 2 that results in both cases (in the form of its radical cation after ionization) was characterized by its IR spectrum and by high-level quantum chemical calculations. Experiment and theory show that the neutral bisketene has only a single conformation where the two ketene moieties are nearly perpendicular, whereas the radical cation is present in two stable planar conformations. The mechanism of the ring-opening reaction, both in the neutral and in the radical cation, is discussed on the basis of calculations. In the latter case it is a nonsynchronous process that involves an avoided crossing of states.
authors: Department of Chemistry, University of Fribourg, CH-1700 Fribourg, Switzerland.
authors: Krzysztof
authors: K
authors: Piech
authors: Thomas
authors: T
authors: Bally
authors: Annette D
authors: AD
authors: Allen
authors: Thomas T
authors: TT
authors: Tidwell
mesh_terms: D002412:Cations / Q000737:chemistry; D003503:Cyclobutanes / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry; D007659:Ketones / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010782:Photolysis; D011789:Quantum Theory
chemical_list: D002412:Cations; D003503:Cyclobutanes; D005609:Free Radicals; D007659:Ketones