SYNTHESIS OF CYCLIC PHOSPHAZENES WITH ISOTHIOCYANATO, THIOURETHANE, AND THIOUREA SIDE GROUPS - X-RAY CRYSTAL-STRUCTURE OF N3P3(NME2)3(NCS)3

Reaction of the cyclic trimeric phosphazene [NP(NCS)2]3 with alcohols, ROH (R = CH3, C2H5, I-C3H7, I-C4H9, and 2-C3H7), in THF resulted in the formation of thiourethane derivatives, [NP(NHCSOR)2]3, via a nongeminal reaction pathway. Reactions of [NP(NCS)2]3 with amines, RNH2 (R = H, CH3, C6H5, I-C4H9, and I-C8H17), in THF yielded thiourea derivatives, [NP-(NHCSNHR)2]3. Interaction of the cyclic tetramer [NP(NCS)2]4 with alcohols and amines also yielded thiourethane and thiourea derivatives, although the reactivity of the tetramer was lower than that of the trimer. The reactivity of the isothiocyanato groups was influenced by the steric and electronic effects of cosubstituent side groups such as trifluoroethoxy or dimethylamino. X-ray crystallographic analysis of cis-nongeminal-[NP(NMe2)(NCS)]3 was carried out, and the structure was compared with those of [NP(NCS)2]3 and [NP(NCS)2]4. cis-nongeminal-[NP(NMe2)(NCS)]3 crystallized in the triclinic space group P1BAR. Unit cell parameters were a = 8.377 (7) angstrom, b = 9.030 (3) angstrom, c = 14.093 (7) angstrom, alpha = 85.55 (3)degrees, beta = 74.91 (5) degrees, gamma = 83.96 (4)degrees. The final R and R(w) values were 0.047 and 0.074. The reactions of the cyclic phosphazenes served as models for those of the analogous macromolecular phosphazenes.