Crystal structures of some compounds containing phosphorus–sulphur bonds

There is conflicting NMR and spectroscopic evidence in the literature for the molecular structure of diphosphine disulphides. Bis(cyclotetramethylene) diphosphine disulphide and bis(cyclopentamethylene) diphosphine disulphide have been investigated by three-dimensional single crystal X-ray techniques to determine their structure, to obtain accurate values for P–P and P→S bond lengths, and to observe any special features resulting from the inclusion of phosphorus in heterocyclic rings. A rough structure of tetramethyl diphosphine disulphide had previously been published based on vary limited two-dimensional data, and this structure has been confirmed and refined from three-dimensional data. [Continues.]