Synthesis of Heavy Cyclodipnictadiphosphanes [ClE(μ-P-Ter)]₂ [E = P, As, Sb, or Bi; Ter = 2,6-bis(2,4,6-trimethylphenyl)phenyl]

A complete series of terphenyl-substituted 1,3-dichloro-1,3-dipnicta-2,4-diphosphanes {[ClE­(μ-P-Ter)]₂, where E = P, As, Sb, or Bi and Ter = 2,6-bis­(2,4,6-trimethylphenyl)­phenyl} was prepared and fully characterized. While the heavy derivatives with E = Sb or Bi can be accessed via conversion of silylated phosphanes with amino-dichloropnictanes and subsequent elimination of TerNH₂, the lighter congeners could be prepared only by a metathesis reaction of [ClBi­(μ-P-Ter)]₂ with PCl₃ and AsCl₃. Spectroscopic and structural data indicate the existence of cis and trans isomers of [ClP­(μ-P-Ter)]₂ in contrast to all heavier derivatives, for which only the trans isomer was obtained.