Polycrystalline and surface complexes (at synthetic sphalerite, ZnS, and galena, PbS) of zinc(II) and lead(II) ions with eight different O,O'-dialkyldithiophosphate (Dtph) substances have been prepared and comparatively studied by means of 31P CP/MAS NMR spectroscopy. The 31P resonances have been assigned to dithiophosphate groups with terminal S,S'-chelating or bridging coordinations in the mono-, bi-, tetra- and polynuclear complexes respectively. The bridging coordination of two neighbouring zinc(II) ions by O,O'-dialkyldithio-phosphate ligands was established at the surface of synthetic sphalerite.
The adsorption mechanism of dialkyldithiophosphate on synthetic galena includes formation of a surface complex as well as surface precipitation. Principally different coordination modes of the reagent were discovered at the surfaces of galena and sphalerite (ie terminal S,S'-chelating coordination to the lead atom).
Derivatives of monothiophosphoric and phosphoric acids were displayed as hydrolysis products of dialkyldithiophosphates at synthetic PbS.