Homoatomic cations: From [P] to [P].

Recent synthetic approaches to a series of [P] salts ( = [F{Al(OR)}], [Al(OR)], and (R = C(CF)); GaCl) overcome limitations in classical synthesis methods that proved unsuitable for phosphorus cations. These salts contain the homopolyatomic cation [P] via (I) oxidation of P with NO[F{Al(OR)}], (II) the arene-stabilized Co(I) sandwich complex [Co(arene)][Al(OR)] [arene = -difluorobenzene (-DFB) and fluorobenzene (FB)], or (III) the reduction of [PCl][GaCl] with Ga[GaCl] as Ga(I) source in the presence of P. Quantum chemical CCSD(T) calculations suggest that [P] formation from [Co(arene)] occurs via the nido-type cluster [(-DFB)CoP], which resembles the isoelectronic, elusive [P]. Apparently, the nido-cation [P] forms intermediately in all reactions, particularly during the Ga(I)-induced reduction of [PCl] and the subsequent pick up of P to yield the final salt [P][GaCl]. The solid-state structure of [P][GaCl] reveals the anticipated -symmetric Zintl-type cage for the [P] cation. Our approaches show great potential to bring other [P] cations from the gas to the condensed phase.