A synthetic and structural study of the formation of cyclic [(RP)nE]− anions and Zintl compounds using E(NMe2)3 (E = As, Sb)

The low-temperature reactions of aliphatic primary phosphines and phosphides with E(NMe2)3 (E = As, Sb) give cyclic anions of the type [(RP)nE]−. At higher temperatures Zintl compounds containing E73− anions are generated. In contrast, related reactions using aryl phosphines lead to the direct formation of Zintl compounds even at low temperature. The reactions of aliphatic and aryl arsines follow a similar pattern to that of the corresponding phosphines. The syntheses and X-ray structures of several complexes containing [(RP)nE]− (n = 3 or 4) and E73− anions are reported.