A Phosphorus(V)-Centered Porphyrin Having Redox- and Air-Stable Axial P-H Bonds.

Phosphorus(V)-centered porphyrins (P(V)-porphyrins) are an important class of functional dyes in many fields of research, and axial ligands on the phosphorus atom affect the electronic properties of P(V)-porphyrins and add functions. Herein, we report on the synthesis and characterization of a hitherto unknown P(V)-porphyrin having hydrogen atoms as axial ligands (1·PF , PF is a counter anion). Synthesis of 1·PF was achieved by treatment of dichloro-derivative (2·Cl) with LiAlH followed by AgPF via hydride reduction accompanied by one-electron reduction and one-electron oxidation. The porphyrin core of 1·PF is nonplanar but considerably ruffled. The cyclic voltammogram of 1·PF exhibits two reversible waves, which indicates redox couples among 1, neutral radical 1, and 1. Compound 1·PF is tolerant toward air despite its PH moiety due to the energetically low-lying HOMO (highest occupied molecular orbital) and σ(P-H) orbitals.