Triorganophosphine–dithiomonometaphosphoryl halides

The title compounds, ethyldiphenylphosphine–dithiomono­metaphosphoryl chloride, EtPh₂PPS₂Cl, C₁₄H₁₅ClP₂S₂, (I), and tris‐n‐propyl­phosphine–di­thio­monometa­phospho­ryl chloride and bromide, ⁿPr₃PPS₂Cl, C₉H₂₁ClP₂S₂, (II), and ⁿPr₃PPS₂Br, C₉H₂₁BrP₂S₂, (III), respectively, are the first phosphine‐stabilized di­thio­monometa­phospho­ryl halides to be structurally characterized. In the tris‐n‐propyl­phosphine derivatives, the central PP donor–acceptor bond becomes longer in the order bromo < chloro < fluoro. Substitution of the tris‐n‐propyl­phosphine group in (II) by the more bulky ethyl­di­phenyl­phosphine group also leads to a longer PP bond. These structural features agree with the observed ³¹P NMR data. In (II) and (III), the central P—P bond coincides with the crystallographic threefold axis, entailing site‐occupational disorder for the S₂Y group.