Electron diffraction study of the molecular structure of trisilylphosphine

The molecular structure of gaseous trisilyphosphine has been determined by the sector-microphotometer method of electron diffraction. The heavy-atom skeleton is found to be pyramidal; the P–Si distance is 2·248 ± 0·003 Å and the Si–P–Si angle 96·45 ± 0·50°. The bond angles at silcon are found to be tetrahedral within experimental error; the Si–H distance is 1·485 ± 0·010 Å. These results supersede conclusions from spectroscopic evidence that the molecule has a planar heavy-atom skeleton.