Complexation of the K+ ions of little soluble K-2[(t)BuP](2) . 1/2 THF (THF = tetrahydrofuran) with 18-crown-6 or [2.2.2]cryptand in THF leads to brown-red solutions which exhibit limited stability at room temperature, The P-31 NMR spectrum consists of two singlets (1:1) which are assigned to the trans and gauche rotamers of the dianion [(t)BuP-P(t)Bu](2-). That dianion undergoes a protonation by the solvent forming the monoanion [((t)Bu)(H)P-P(t)Bu](-), which has been characterized by P-31 NMR spectroscopy. In addition, the brown-red solutions contain a paramagnetic species, for which the EPR spectrum revealed a 1:2:1 triplet caused by the hitherto unknown diphosphene radical anion [(t)BuP=P(t)Bu].(-) (g(iso) = 2.0103), These reactions of the dianion [(t)BuP-P(t)Bu](2-) on complexation of the K+ ions occur also at -40 degrees C and can be attributed to a tendency to reduce the Coulombic repulsion between the adjacent negative charges. The homologous triphosphene radical anion [(t)BuP-((t)Bu)P-P(t)Bu].(-) could be generated by reduction of the cyclic triphosphane ((t)BuP)(3) on a potassium mirror. The new triphosphene radical anion was identified by its EPR spectrum which showed a triplet of doublets (g(iso) = 2.0098). Finally, reduction of the neutral valence isoelectronic cyclic diphosphirane (CH3)(2)C((t)BuP)2 on a potassium mirror yields the radical anion [(CH3)(2)C((t)BuP)(2)].(-), which exhibits a 1:2:1 triplet in the EPR spectrum (g(iso) = 2.0060), The triphosphene radical anion [(t)BuP-((t)Bu)P-P(t)Bu].(-) is related to the radical anions O-3.(-), S-3.(-) and P-3(. 4-), but in contrast to O-3.(-) and S-3.(-) the pattern of hyperfine coupling constants is "reversed". Quantum-chemical calculations of [P3H3].(-) suggest an open-chain structure for [(t)BuP-((t)Bu)P-P(t)Bu].(-). A possible explanation is given for the reversion of the hyperfine coupling pattern due to the shape of the highest occupied orbital. The adiabatic electron affinities are calculated for two possible structures of [P3H3].(-).