NMR and Raman spectroscopies have been applied to characterise the diisobutyldithiophosphinate (DIBDTPI) compounds of sodium, copper, silver and gold, diisobutyldithiophosphinic acid (DIBDTPIH), and the oxidation product bis(diisobutylthiophosphoryl)disulfide (DIBDTPI)2 in order to provide a basis for investigating the interaction of the flotation collector, NaDIBDTPI, with the coinage metal surfaces. Spectra for the various species in the solid state and in solution obtained by both techniques are interpreted in terms of the symmetry and conformation of the molecule. Raman spectroscopy provides an effective means of distinguishing between coinage metal DIBDTPI compounds and (DIBDTPI)2.