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A series of closely related polyphosphazenes with propoxy, pentoxy, hexoxy, octoxy, isostearyloxy, and 2-(2-methoxyethoxy)ethoxy (MEE) side groups, together with cosubstituent species with both the alkoxy and MEE side chains, were studied for their morphology and miscibility with oligoisobutylene (OIB). All the pure polymers except one had a single glass transition temperature. The exception was the species with both isostearyloxy and MEE side groups, which underwent two low-temperature second-order transitions, even though 31P NMR spectra indicated the absence of a block-type structure. For the single-substituent macromolecules, the solubility at 80 ° C in OIB increased as the length of the unbranched alkoxy side groups rose from propoxy to octoxy (from 1 to 11 wt/wt%). However, the polymer with two isostearyloxy side chains per repeat unit had a low solubility in OIB (3 wt/wt%), and the species with the two MEE side groups on every repeat unit was totally insoluble. When both alkoxy and MEE side groups were present, the solubility in OIB was also low (0-3%), except for the species with both isostearyloxy and MEE side groups, which was soluble in OIB at a level of 21 wt/wt% at 80 ° C, and showed Tg evidence of polymer/oligomer miscibility even at -80 ° C. Explanations are suggested for the unusual behavior of this polymer. POLYM. ENG. SCI., 51:1693-1700, 2011. ©2011 Society of Plastics Engineers, INTRODUCTION Polyphosphazenes are hybrid inorganic-organic macromolecules in which the properties are determined by both the inorganic phosphorus-nitrogen backbone and the organic side groups. The backbone imparts properties such as fire [...]

The study of the single-crystal X-ray structures of both the trans bis and the tris isomers of the compound, 2,2'-dioxybiphenyl-chloro-cyclotetraphosphazenes confirms its flexibility that gives rise to different crystalline forms obtained from the same system. The calculated low-energy barriers and the highly disordered phosphazene ring conformations observed in the solid state support the flexibility of the phosphazene ring.

The synthesis and characterization of two novel fluorophosphazene derived from cobaltocyclopentadienylmetallacycles is reported and a hitherto unknown synthetic route for making aryl bridged fluorinated cyclophosphazenes by the reaction of the metallacycles with substituted acetylenes is provided. These cobaltametallocycles are possible precursors for making novel acetylene-trimerized aryl compounds as well as [[eta].sup.5]-Cp]Co[[[eta].sup.4]-R4C4] metallocenes.

The mechanism of the aza-Wittig reaction between phosphazenes and aldehydes is studied computationally using density functional theory methods. It is found that the reaction consists of a tandem [2+2] cycloaddition-cycloreversion sequence in which pi and sigma orbitals as well as lone pairs are involved.

Variable-temperature (super 2)H NMR investigations are carried out to study the molecular behavior of predeuterated benzene in the inclusion compound with tris(1,2-dioxyphenyl)cyclotriphosphazene. A quantitative analysis of the experimental data is achieved by appropriate computer simulations taking into account various motions of the benzene guests.

Addition of chiral shift reagent (CSR) or chiral solvating agent (CRA) to separate meso and racemic forms of some diastereoisomeric single-bridged cyclophosphazene compounds causes doubling of 31P NMR signals for both isomers. The anomalous behavior on addition of CSR/CSA is only found for meso forms of cyclophosphazene compounds.

The reinvestigation of the molecular structure of the parent molecule N(sub 4)P(sub 4)F(sub 8) by using x-ray diffraction, gas electron diffraction and differential scanning calorimetry is described. The results from each of these measurements support a nonplanar eight-membered ring for N(sub 4)P(sub 4)F(sub 8) that is puckered and that undergoes a phase transition at -74 degrees C.

The synthesis via reaction of [C.sub.[alpha],[C.sub.ortho] dilithiated phosphazene with CuBr and structural characterization of the binuclear mixed valence [[Cu.sup.I]([N.sub.2])/[Cu.sup.III]([C.sub.4])] complex displaying a metal-metal bond, as well as its applications in cyclopropanation and oxidation reactions, are described.

The reactions of cyclotriphosphazenes containing P-NHR groups in the side chain in the presence of a strong base are examined. A stable cis-cyclophosphazene bridged with a four-membered cyclophosphazene ring in a spiro arrangement is obtained with a linear secondary amine and a biscyclophosphazene bridged with an eight-membered cyclophosphazene ring in an ansa arrangement is obtained with a cyclic secondary amine.

The reactions of [[[eta].sup.5]-MeOC(O)[C.sub.5][H.sub.4]]Co[[[eta].sup.4]-COD] where COD = 1,5-cyclooctadiene) with PhC[triple bond]C[P.sub.3][N.sub.3][F.sub.5] along with cycloalkenes or indene, which has formed mono and bis fluorophosphazene derived cyclohexadiene complexes of cobalt, are described. The mechanism of the formation of cyclohexadiene by using CpCo based reagents and the experimental evidence for a metallacyclopentadiene pathway for the same are provided.

Triphosphazene, 1,3,5-triazo-2,4,6-triphosphorine-2,2,4,4,6,6-chloride (TAPC), has served as an efficient catalyst for the Beckmann rearrangement of ketoximes to lactams. The rearrangement of cyclohexanone oxime to [epsilon]-caprolactam is achieved by TAPC and this method has provided an environmental friendly route to nylon-6 without formation of any salt.

The aluminum-containing heterophosphazene N(PCl2NMe)2AlMeCl is prepared through a rare skeletal transmetalation reaction involving the boratophosphazene N(PCl2NMe)2BCl2 and AlMe3. Treatment of N(PCl2NMe)2AIMeCl with Ag[PF6] led to the insertion of phosphorus in place of aluminum to form the novel zwitterionic fluorinated phosphorus(V) heterocycle N(PCl2NMe)2PF4.

A synthetic strategy is developed to prepare cyclotriphosphazenes that bear polycatenar aromatic esters as promesogenic units linked to phosphorus atoms. The columnar organizations in cyclotriphosphazenes can be explained by a discotic structure consisting of promesogenic cores arranged approximately parallel to the cyclotriphosphazene ring.

The reaction of hexakis(cyclohexylamino) cyclotriphosphazene [NO(CyNH)(sub 2)](sub 3) with phosphorous trichloride yields [NP(CyN)(sub 2)PCl](sub 3), which contains three four-membered phosphazane rings fused in spyrocyclic fashion to a central six-membered phosphazane ring. It is the first structurally characterized compound that comprises both phosphazene and phosphazane rings.

An effort is made to show that cyclophosphazenes, (RNH)(sub 6)P3N3 in conjunction with silver salts can produce supramolecular coordination compounds by forming of linear N-Ag-N connections via N(ring). Different diagrams demonstrating the details of crystal structure are presented.

An improved preparation of [Cl3P=N=PCl3]-Cal has been achieved, and the construction of novel phosphazene chains and macrocycles from this versatile reagent is described. Studies showing the construction of new macrocycles from the linear phosphazene chains are presented.

A two-step asymmetric synthesis of disubstituted N-tosyl aziridines is presented using a phosphane base. This two-step asymmetric synthesis could be easily used on gram quantities and involves no unstable/hazardous reagent.

The synthesis and structures of unprecedented cyclocarbophosphazene-containing tetramers, where the individual six-membered carbophosphazene inorganic rings are tethered together by P-O-P and P-O-Cu bonds are reported. These structural entities are unprecedented among heterocyclophosphazenes.