Description:
<jats:title>Abstract</jats:title><jats:p>The electronic structure of [4.2.2]propella‐2,4,7,9‐tetraene (<jats:bold>1</jats:bold>), 2,5‐etheno[4.2.2]propella‐3,7,9‐triene (<jats:bold>2</jats:bold>), and of several hydrogenated derivatives of <jats:bold>2</jats:bold> has been investigated using He(I) PE spectroscopy and MO calculations. It is found that in <jats:bold>2</jats:bold> the 1,4‐cyclohexadiene moiety interacts considerably with the bicyclo[2.2.0]hexadiene unit, while in <jats:bold>1</jats:bold> the interaction between the butadiene fragment and the <jats:italic>Dewar</jats:italic> benzene unit is minute. The syntheses of <jats:bold>3–5</jats:bold> are reported.</jats:p>