Isolable Phospha- and Arsaalumenes

The combination of (AlCp*)(4), a source of monomeric :AlCp* at elevated temperatures, with (Dip)TerPriPMe(3) (Pn = P, As), so-called pnicta-Wittig reagents, at 80 degrees C cleanly gives the pnictaalumenes (Dip)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 (Mes)TerPPMe(3), the reaction with 2 equiv of :AlCp* or :AlCp* afforded the three-membered 2 pi-aromatic ring systems (Mes)TerP(AlCpx)(2) (x = 3t, *).

Automated summary

Combining (AlCp*)(4), a source of monomeric :AlCp* at elevated temperatures, with (Dip)TerPriPMe(3) (Pn = P, As) cleanly produces pnictaalumenes (Dip)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 at 80 degrees C. On the other hand, using (Mes)TerPPMe(3) in reaction with 2 equiv of :AlCp* or :AlCp* results in the formation of three-membered 2 pi-aromatic ring systems (Mes)TerP(AlCpx)(2) (x = 3t, *).