Cover Feature: Unusually Long‐Wavelength Emissions of Cyclopropanes: New Insight into C−C Bond Homolysis (Chem. Eur. J. 30/2018)

Abstract

Bond homolysis (BHo) is a fundamental concept in chemical‐bonding phenomena. To date, research studies on the BHo concept have provided crucial information for understanding the nature of chemical bonding and reactions. Two potential‐energy minima, a σ‐bonding isomer and a singlet‐diradical isomer, have been known to exist in carbon–carbon BHo. In the present study, a third isomer, that is, a puckered singlet diradical exhibiting unstructured long‐wavelength fluorescence beyond 460 nm, was first observed in the excited states of 1,4‐diarylbicyclo[2.1.0]pentane derivatives. This finding provides new insight into carbon–carbon bond‐breaking and ‐forming processes. For more information, see the Communication by M. Abe, H.‐H. G. Tsai et al. on page 7595.