Gas-phase structures of aminodifluorophosphines determined using electron diffraction data and computational techniques.

The molecular structures of a family of eight aminodifluorophosphines, (PF2)NRR'(R, R' = H, CH3, SiH3, GeH3, PF2), have been redetermined using gas-phase electron diffraction data and high-level ab initio molecular-orbital calculations. The SARACEN method has allowed the application of flexible restraints, giving greater accuracy and precision of structure, while the SHRINK program has allowed curvilinear corrections for vibrational effects to be applied to intramolecular distances. The more accurate structures of these eight compounds show consistent patterns of effects attributable to the various substituents, while conformations are dominated by the requirement that adjacent phosphorus and nitrogen lone pairs of electrons should be orthogonal.