CYCLIC S-N COMPOUNDS AND PHOSPHORUS REAGENTS .15. SYNTHESIS, SPECTRALAND X-RAY STRUCTURAL CHARACTERIZATION OF (PH)(DCA)(R)P=N-S3N3 [R=(C2H5)(2)N-(N-C4H9)(2)N-]

Room-temperature reactions of asymmetric phosphines, (Ph)(DCA)(R)P (R = Et(2)N-, Bu(2)(n)N-) with S4N4 in acetonitrile afforded phosphinimin ocyclotrithiazenes, (Ph)(DCA)(R)P=N-S3N3 (R = Et(2)N-, I; Bu(2)(n)N-, II) in modest yields (ca 50%). The heterocycles have been characterize d by spectroscopic [IR, UV-vis, NMR (H-1 and P-31) and mass] and singl e crystal X-ray diffraction methods. Strikingly, the angle at P-N(4)-S (1) is 135 degrees in I, the largest observed so far and is 119.3 degr ees in II. This is also accompanied by the shortest exocyclic S(1)-N(4 ) bond length of 1.537 Angstrom observed in the case of I. In the unit cell of II, two types of molecules with slightly differing degree of deviation of the tricoordinate sulfur (0.664 and 0.673 Angstrom from t he mean plane [N(1)-S(2)-N(2)-S(3)-N(3)] are observed. Copyright (C) 1 997 Elsevier Science Ltd.