The Reaction of Diethylthiophosphinyl Iodide, Et2P(S)I, with Nucleophiles

The compound Me2AsSI can exist in two different forms, either as dimethylarsinosulfenyl iodide [or (iodothio)dimethylarsane)], Me2As–S–I (A), or as dimethylthioarsinyl iodide (or dimethylarsinothioic iodide), Me2As(S)–I (B). To confirm that the structure of the product of the reaction between Bunsen's cacodyl disulfide Me2As(S)–S–AsMe2 and iodine is A and not B, the known diethylthiophosphinyl iodide (or diethylphosphinothioic iodide), Et2P(S)–I (2) was prepared and its hydrolytic stability and reactivity towards a variety of nitrogen, phosphorus(III), arsenic(III), oxygen, and sulfur(II) nucleophiles were studied. The results indicated that only a few reactions of 2 resembled those of A, thus strengthening the proposal that the reaction of Bunsen's cacodyl disulfide with iodine produced A and not B. A series of 31P NMR chemical shifts of diethylthiophosphinyl moiety is also reported. Et2P(S)–DMAP, synthesized and isolated during the presented study, is the ethyl analogue of Me2P(S)–DMAP, previously described as an important molecule. In our case, Et2P(S)–DMAP was found to be a good intermediate for the synthesis of phosphoryl or thiophosphoryl derivatives since it was more reactive than 2 towards nucleophiles.