Synthesis and structure of P7[Si(SiMe3)3]3 (tri(hypersilyl)heptaphosphanortricyclane)

By reaction of sodium-potassium phosphide (prepared from white or red phosphorus and sodium-potassium alloy) and chlorotris(trimethylsilyl)silane, P-7[Si(SiMe3)(3)](3) has been prepared in high yields. An X-ray analysis proved that the molecule is composed of a P-7-nortricyclane cage substituted with three Si(SiMe3)(3) groups and that two enantiomers are present in crystals grown from benzene. The P-31 NMR spectrum shows the complex splitting pattern of an A[MX](3) spin system. P-31 chemical shifts and P-31, P-31 one-bond and two-bond coupling constants have been calculated by numerical simulation of the spectrum.