Symmetrical and Unsymmetrical Triphosphenium Ions

Abstract

The triphenylphosphenium ion in 1, can be looked upon as a triphenylphosphane complex of phosphorus. 1 is formed by the joint action of Ph3P and AlCl3 on PCl3. Surprisingly, the central P atom in 1 can be protonated; the “ligands” can be successively replaced by more strongly basic phosphanes, so that unsymmetrical triphosphenium ions are also accessible. The length of the PP bond in 1 lies between that of a PP single bond and a PP double bond.