Molecular structures of silylphosphine, silylmethylphosphine, and silyldimethylphosphine: an electron diffraction study

The molecular structures of silylphosphine, silylmethylphosphine, and silyldimethylphosphine have been determined in the vapour phase by the sector-microphotometer method of electron diffraction. The Si–P bond lengths are, respectively 2·249(3), 2·248(3), and 2·245(3)Å. Substitution of SiH3 for H in mono- and di-methylphosphine does not appear to influence the C–P bond length. The C–P–C and C–P–Si angles lie in the range 99–101°, similar to the C–P–C angles in the methyl phosphines, but in contrast to the structural variations found in the series (H3Si)nNMe3 –n. The bonding in the silyl phosphines is discussed.