Dr Bruce Tattershall
Lecturer in Chemistry (retired)

Identification by NMR of polyphosphorus ring and cage compounds.

Research Interests

Since a first publication in this field in 1984, we have discovered many new polycyclic or cage compounds based on the P4 tetrahedron.  These have included new phosphorus halides, such as P4Br2 or P7I3, and derivatives of several new phosphorus chalcogenide skeletons such as P5S2X or P3Se4X, as well as a wide range of compounds P4E3XY based on the previously known two P4S3I2 skeletons.  E may be any combination of sulfur and selenium, and X and Y are halide, pseudohalide or a range of N-, O-, P- or S-centred organic groups.

Few of these compounds have been isolatable, because of ring-opening polymerisation, so positive identification has been by complete analysis of  31P spectra, or of  77Se spectra where present, of the compounds in solution.  This required accumulation of a detailed knowledge of the relationships between molecular structure and the systems of NMR coupling constants and chemical shifts observed within the cage skeletons.  We have shown that this knowledge is transferable from known to new cage skeletons, enabling their identification.  Apart from a few crystal structures in this field, knowledge of molecular structure comes from ab initio calculations, which I continue to carry out, and which often yield useful predictions of relative NMR chemical shifts, as an aid to their assignment.  My published structural models may be found at the website above, as may my freely downloadable software for the simulation or fitting of NMR spectra, as well as software for use in teaching about mass spectrum isotope patterns or molecular orbitals.

Our most recent publications have been the first studies of phosphorus sulfide skeletons with chiral  substituents.  We were able to use diastereomeric differences in NMR properties to assign absolute configurations, and to model bond rotamers which were observed at low temperature.

Selected Publications