The Reaction of Bunsen's Cacodyl Disulfide,Me2As(S)‐S‐AsMe2, with Iodine: Preparation and Properties of Dimethylarsinosulfenyl Iodide,Me2As‐S‐I

Bunsen's cacodyl disulfide, Me₂As(S)‐S‐AsMe₂ ( 1 ), reacted with iodine giving the novel dimethylarsinosulfenyl iodide, Me₂As‐S‐I ( 3 ) although theoretical calculations indicated that the As^V compound Me₂As(S)‐I ( 4 ) was more stable in the gas phase. The oily product was stable neat and as a solution in CDCl₃ at +4 °C and –20 °C for at least 15 d. Light, H₂O, H₂O₂, and Zn dust, but not NaI or Ag, decomposed it. Compound 3 did not interact with Ph₃N, with Ph₂NH and PhNH₂ it interacted but not reacted. 3 was decomposed by piperidine, with pyridine and 4‐dimethylaminopyridine it interacted and produced Me₂As‐SS‐AsMe₂ ( 2 ) and I₂ that formed charge transfer complexes Base · I₂, whereas Et₃N decomposed 3 , and 3Et₃N · 2I₂ was isolated. 3 was desulfurized by Ph₃P and (Me₂N)₃P completely, and by (PhO)₃P and (PhS)₃P partially. The reactions of 3 with (Me₂N)₃P, (PhS)₃P, and (EtO)₃P were complicated. From the As^III nucleophiles, only Ph₃As was bound, while (PhS)₃As reacted slowly in a complicated manner with 3 . No interaction of 3 with MeOH or PhOH was observed but NaOH, Ag₂O, and PhONa decomposed it. Thiophenol produced traces of Me₂As‐SPh ( 10 ) and sodium thiophenolate attacked mainly at As^III of 3 . Thus, externally stabilized sulfenium ions of the type Me₂As‐S‐Nu⁺I^– were not obtained.