Potential energy surfaces for all-trans [P.sub.5][H.sub.6.sup.+] and [P.sub.5][Mn.sub.6.sup.+] may be less complicated than anticipated

The synthesis, structure and pseudorotation of a family of cyclotetraphosphinophosphonium ions are described. The [P.sub.5][H.sub.6.sup.+] and [P.sub.5][Me.sub.6.sup.+] potential surfaces are quantitatively very different from that of the tetrahydrofuran.