An AlAl One‐Electron π Bond

Not a reductive rupture, but a strengthening of the AlAl bond is the result of the reduction of the dialane 1 with lithium. The salt isolated after addition of TMEDA contains the radical anion of 1, in which, as results of an X-ray structural analysis show, the AlC bonds are distinctly longer (+0.06 Å) and the AlAl bond considerably shorter (−0.13 Å) than in 1 itself. These findings are in accord with results of MO calculations, which indicate a stabilization of the AlAl bond by the additional electron.