Phosphorus(III) Cations Supported by a PNP Pincer Ligand and Sub‐Stoichiometric Generation of P 4 from Thermolysis of a Nickel Insertion Product

Neutral, mono‐, and dicationic phosphorus(III) compounds are accessible with a supporting PNP pincer ligand (PNP=[4‐Me‐2‐ i Pr 2 P‐C 6 H 3 ) 2 N]). Reaction of (PNP)H with PCl 3 and n Bu 3 N furnished (PNP)PCl 2 ( 1 ), which displays a highly temperature‐dependent structure in solution. Synthesis and characterization by NMR spectroscopy and X‐ray crystallography of Cl/Br‐scrambled derivatives, a monocationic derivative [(PNP)PCl][HCB 11 H 11 ] ( 4 ), and the dicationic derivatives [(PNP)P][OTf] 2 ( 5 ), [(PNP)P][B(C 6 F 5 ) 4 ] 2 ( 6 ), [(PNP)P][B 12 Cl 12 ] ( 7 ) established that 1 not only undergoes several fluxional processes in solution but also possesses a temperature‐dependent ground state structure. Reaction of 1 with a Ni 0 source initially leads to a phosphine–phosphinidene complex, followed by thermal generation of P 4 .