A twist on Hellwinkel’s salt, [P(2,2′-biphenyl)2]+[P(2,2′-biphenyl)3]–

Treating PCl5 with C12H8Li2, generated from either C12H10, C12H8Br2, or C12H8I2, affords three products in different ratios depending on the source of the lithiated biphenyl. Hellwinkel's salt [P(C12H8)(2)][P(C12H8)(3)] ([1][2]) and another product [P(C12H8)(C24H16)][P(C12H8)(3)] ([1'][2]) were obtained by reacting PCl5 with 2,2'-dilithiobiphenyl [Route A: 2.5 equiv.; obtained from biphenyl, n-BuLi, and TMEDA; Route B: 3.0 equiv.; obtained from 2,2'-diiodobiphenyl and n-BuLi; Route C: 4.0 equiv.; obtained from 2,2'-dibromobiphenyl and n-BuLi]. The synthesis, isolation, and characterization of the chiral spiro-compound [1'][2] and the characterization of the pentavalent phosphorane [P(C12H8)(2)(C12H9)] (3) are reported. The complex [1'][2] was characterized by P-31{H-1} NMR spectroscopy, X-ray crystallography, and mass spectrometry. The pentavalent compound (3) was characterized by P-31{H-1} NMR spectroscopy and X-ray crystallography.