CYCLIC SULFUR NITROGEN-COMPOUNDS AND PHOSPHORUS REAGENTS .12. REACTIONS OF S4N4 WITH (2-PYRIDYLAMINO) PHOSPHINES

Tetrasulfurtetranitride, S4N4 reacts with (2-pyridylamino)-diphenylpho sphine in MeCN at room temperature to form the cyclotrithiazene (NC5H4 NH)-Ph2PN-S3N3 (1) in good yield. By contrast, the cyclophosphathiazen es Ph2PS2N3(2) and 1,5(Ph2P)2S2N4 (3) are isolated from the same react ion mixture under reflux conditions. In solution, compound 1 is found to be transformed into 2. The reaction of S4N4 with (2-pyridylamino)ph enyl(dicyclohexylamino)phosphine in MeCN at room temperature affords P h(DCA)PS2N3 (4) (DCA = dicylohexylamino) as the only reaction product. This on treatment with norbornadiene produces the addition product Ph (DCA)PS2N3.C7H8 (5). The structure of 4 has been established by X-ray diffraction. Its PSN ring adopts a skew boat conformation with S-N bon d lengths varying from 1.574(4) to 1.606(4) angstrom. The mean value o f the endocyclic P-N bonds amounts to 1.618(3) angstrom.