The stable lithium diphosphene anionradical, [Li(dme)3]+[TbtPPTbt]− (dme: 1,2-dimethoxyethane, Tbt: 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl), was readily synthesized by the one-electron reduction of the corresponding neutral diphosphene (TbtPPTbt). The molecular structure of the diphosphene anionradical was discussed in detail on the basis of its ESR, UV–Vis and Raman spectra, and theoretical