Synthesis and structure of [(ButN)P(μ-NBut)2P(PCy)Li2·thf]2; an unusual cage compound containing an amido/phosphido functionalised [(ButN)P(μ-NBut)2P(PCy)]2− dianion (Cy = C6H11)

The reaction of [((BuNH)-N-t)P(mu-NBut)(2)PCl] (1) with CyPHLi and (BuLi)-Li-n in toluene gives [((BuN)-N-t)P(mu-NBut)(2)P(PCy)Li-2. thf](2) (2), an unusual aggregate containing the first example of a phosphine-functionalised cyclodiphosphazane anion [((BuN)-N-t)P(mu-NBut)(2)P(PCy)](2-).