Preparation and molecular structure of silylaminodifluorophosphine

Abstract

Silylaminodifluorophosphine has been prepared in high yield from the reaction between silyl bromide and aminodifluorophosphine; the compound decomposes slowly at room temperature. Its i.r. spectrum indicates that there are two conformers in the vapour at room temperature, but that in the solid at 77 K one conformer is much the more stable; the electron diffraction pattern of the vapour can also be interpreted in terms of the presence of two conformers, in each of which there are short H⋯F non-bonded distances. In each conformer the main structural parameters are taken to be the same, and are found to be : r(Si–N)= 1·720 ± 0·008; r(N–P)= 1·657 ± 0·007; r(P–F)= 1·574 ± 0·003 Å; ∠SiNP = 127·9 ± 0·7°; ∠FPF = 100·8 ± 1·2°; ∠FPN = 95·6°. The n.m.r. spectra (¹H,¹⁹F) of SiH₃¹⁴NHPF₂ and SiH₃¹⁵NHPF₂ at room temperature show that the SiH protons behave as equivalent, as do the F nuclei, and that any NH exchange is slow on the n.m.r. timescale.