Synthesis and structure of nongeminally substituted cyclic phosphazenes with haloalkyl and thioester functional groups.

Nongeminally substituted cyclic phosphazenes with various haloalkyl substituents were prepared using deprotonation-substitution reactions at the methyl groups of the cis isomers of nongeminally substituted cis-[Me(Ph)P=N]3, 2. Treatment of 2 with n-BuLi followed by reaction with organic halogenated reagents (RX=C2Cl6, BrC(O)CMe2Br, and ICH2COOEt) at low temperature afforded the various cyclic derivatives cis-[(XCH2)(Ph)PN]3 (3, X=Cl, 4, Br, and 5, I). The mono- and dibromoalkyl derivatives, cis-[Ph3(BrCH2)Me2P3N3], 6, and [Ph3(BrCH2)2MeP3N3], 7, were also isolated along with 4 when the electrophile was dibromoethane. Reaction of cis-[Ph(BrCH2)PN]3, 4, with KSC(O)Me gave cis-[Ph(MeC(O)SCH2)PN]3, 8. The structures of all the cis cyclic phosphazenes were determined by NMR spectroscopy and X-ray diffraction. All retained the basketlike shape with the hydrophobic phenyl groups opposite the haloalkyl groups on the P3N3 ring. Thermal analysis of the new cyclic trimers indicates that ring-opening polymerization does not occur. The melting points and the thermal stabilities of haloalkyl cyclophosphazenes were higher than those of the parent compound 2.

Isolation and characterization of nongeminal cyclic methylphenylphosphazene tetramers.

Heating pure samples of the cyclic phosphazenes, cis- or trans-[Me(Ph)PN](3), yielded mixtures of the cis and trans isomers of the cyclic phosphazene trimers, [Me(Ph)PN](3), and all four geometric isomers of the tetramers, [Me(Ph)PN](4). Varying the temperature and heating times changes the ratio of these components. Following the thermolysis by NMR spectroscopy indicated that only a mixture of the two isomeric trimers occurred initially. Longer heating times produced mixtures of the isomers of the tetramer. Column chromatography and solubility differences were used to separate each of the isomers of the tetramer. Spectroscopic and X-ray crystallographic studies suggest that the four different geometrical isomers of the tetramer can be described as cone, partial cone, 1,2-alternate, and 1,3-alternate by analogy to calix[4]arene.

Deprotonation-substitution reactions of cyclic methylphenylphosphazenes: synthesis and structures of nongeminal P-ethyl, P-phenyl cyclotriphosphazenes.

The deprotonation-substitution reactions of both the cis and trans isomers of nongeminally substituted [(Me)(Ph)P=N](3) were investigated. Treatment of the trans isomer, 1, with 3 equiv of n-BuLi followed by 3 equiv of MeI gave only nongeminal trans-[(Et)(Ph)P=N](3), 3, while the same reaction sequence on cis-[(Me)(Ph)P=N](3), 2, gave a mixture of nongeminal di- and trisubstitution products, cis-Et(2)MePh(3)P(3)N(3), 4, and cis-Et(3)Ph(3)P(3)N(3), 5. These trimers were separated by column chromatography. No changes in the stereochemistry of the rings occurred during these reactions. Compound 4 was also prepared using 2 equiv of the reactants and was then converted to 5 by treatment with a single equivalent of BuLi and MeI. Thermal analysis of the new cyclic trimers indicates that ring-opening polymerization does not occur and that sublimation occurs at ca. 300 degrees C. The structures of 4 and 5, obtained by X-ray diffraction, illustrate the basketlike shape of these molecules with an aromatic bowl formed by the phenyl rings on the top rim, while the structure of 3 clearly shows the trans orientation of the substituents. Crystal data for trans-Et(3)Ph(3)P(3)N(3), 3, at 20 degrees C are as follows: C(24)H(30)N(3)P(3) monoclinic, a = 14.273(2) A, b = 9.370(2) A, c = 19.600(3) A, beta = 107.16(1) degrees, P2(1/n), Z = 4. Crystal data for cis-Et(2)MePh(3)P(3)N(3), 4, at 20 degrees C are as follows: C(23)H(28)N(3)P(3), triclinic, a = 10.276(2) A, b = 10.699(2) A, c = 11.925(2) A, alpha = 72.07(2) degrees, beta = 73.79(1) degrees, gamma = 85.87(1) degrees, P1, Z = 2. Crystal data for cis-Et(3)Ph(3)P(3)N(3), 5, at 20 degrees C are as follows: C(24)H(30)N(3)P(3) monoclinic, a = 29.488(2) A, b = 9.8391(1) A, c = 21.172(2) A, beta = 126.30(1) degrees, C2/c, Z = 8.

Reactions of N-silylphosphoranimines with alcohols: synthesis and structure of cyclotriphosphazenes with nongeminal methyl and phenyl substituents.

The reactions of Me(3)SiN=P(OR")RR'(R" = Ph, CH(2)CF(3); R, R' = Me, Ph) with alcohols were investigated. With nonequivalent amounts of CF(3)CH(2)OH, the reactions produced high yields of the cyclic phosphazene (Me(2)PN)(3) and both the cis and trans isomers of nongeminally substituted [(Ph)(Me)PN](3). The isomers of this new cyclic phosphazene were separated by column chromatography and characterized by NMR and IR spectroscopy, elemental analysis, and X-ray crystallography. Crystals of the cis isomer 6a have a monoclinic crystal system, while the trans isomer 6b has a triclinic crystal system with two different molecules in an asymmetric unit. The bond lengths and bond angles are very similar to those of the simpler cyclic trimers (Me(2)PN)(3) and (Ph(2)PN)(3.) A likely pathway for the formation of these compounds is discussed.