Isolable Phospha- and Arsaalumenes.

The combination of (AlCp*), a source of monomeric :AlCp* at elevated temperatures, with TerPnPMe (Pn = P, As), so-called pnicta-Wittig reagents, at 80 °C cleanly gives the pnictaalumenes TerPnAlCp* with polarized Pn-Al double bonds and intramolecular stabilization through interactions of Al with a flanking aryl group of the terphenyl substituent on Pn. In contrast, using TerPPMe, the reaction with 2 equiv of :AlCp or :AlCp* afforded the three-membered 2π-aromatic ring systems TerP(AlCp) ( = 3t, *).