Cover Picture: Synthesis and Structure of Tetraarylcumulenes: Characterization of Bond-Length Alternation versus Molecule Length (Angew. Chem. Int. Ed. 6/2013)



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sp-Hybridized carbon allotropes based on a polyyne framework are well documented, while properties of the cumulenic form of these allotropes remain mysterious. In their Communication on page 1817 ff., R. R. Tykwinski and co-workers shed new light on the properties of cumulenes (such as bond length alternation) through the synthesis, spectroscopic study, and crystallographic analysis of cumulenes that contain up to nine consecutive double bonds (i.e., a [9]cumulene). Cover art: Annie Tykwinski; based on a concept from D. Wendinger.