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.