How to tame planar and main group metal-substituted onium ions of phosphorus and arsenic

The P+-transfer abilities of 1,1,1,3,3,3-hexakis(dimethylamino)-triphosphenium tetraphenylborate were investigated. Reaction with Schwartz reagent lead to the first planar tetracoordinated phosphonium salt P[ZrCp2H](4)+BPh4+. The theoretical background of this unusual planar geometry at the phosphorus atom is discussed. The first arsenic analogue [As(P(NMe2)(3))2]+BPh4- of the respective triphosphenium salt was prepared, which surprisingly can act as a P+- and As+-transfer reagent at the same time. Furthermore, the synthesis of perstannylated ([(Me3Sn)(4)E]OSO2CF3, E=N, P) and persilylated ([(Me3Si)(4)E](+) B(C6F5)(4)(-), E = P, As) onium ions of nitrogen, phosphorus, and arsenic are reported, which are potential starting materials for an independent access to E[ZrCp2X](4) salts.