A new lithium salt of diphosphane, (iPr₂N)PhP-P(SiMe₃)Li (2), featuring two electronically differentiated substituents, is presented. Its reaction with benzophenone was then carried out, yielding a novel phosphanylphosphaalkene (3). The isolated compound was subsequently treated with nBuLi and PhLi to obtain stable activators (3a and 3b) of the potential polymerization of phosphorus-rich compounds.