Cyclic sulphur–nitrogen compounds and phosphorus reagents. Part 2. Reactions of tetrasulphur tetranitride with (morpholino)diphenylphosphine. First observation of the ring contraction of 1,5-[(OC4H8N)Ph2PN]2S4N4 to (OC4H8N)Ph2PNS3N3 in solution

Abstract

(Morpholino)diphenylphosphine, unlike PPh₃, gives only two new compounds, (OC₄H₈N)Ph₂PNS₃N₃, (1), and 1,5-[(OC₄H₈N)Ph₂PN]₂S₄N₄, (2), on reacting with S₄N₄. The reaction temperature, solvent, and mole ratio of the reactants are critically important in their synthesis. For the first a ring contraction of compound (2) to compound (1) in solution at room temperature has been observed and evidence for the elimination of the ‘NSR’ group (R = phosphinimino group) obtained.