Radical-substituted allenes as high-spin species and subunits of organic ferromagnets Original Research Article

Allenes, substituted with radicalic groups (CH2⋅, NH2⋅+, HN–O⋅) at the terminal carbon atoms, have been investigated theoretically by ab initio methods. It is shown that the 1,3-dimethyleneallene and the 1,3-diaminoallene dication are molecules with triplet ground states due to the formation of carbene-like triplet state structures. In contrast, the closed-shell singlet state and the triplet state are degenerate for the 1,3-dinitroxideallene due to orthogonally arranged and hence decoupled π-electron systems.