Triplet nitrenes and highly strained, closed-shell 2,3-bridged 2H-azirines undergo quite different dimerization reactions to give unsymmetrical monocyclic or symmetrical tricyclic products. The picture schematically illustrates these pathways on singlet and triplet hypersurfaces. In their Full Paper on page 1128 ff., K. Banert, E.-U. Würthwein, S. Grimme, et al. investigated, both experimentally and by quantum chemical methods, the intermediates that resulted from the irradiation of cyclic vinyl azides as a function of ring size, substitution pattern, and reaction conditions.