Unexpected formation of ansa isomers enabled by phosphazene ring flexibility in the reactions of cyclotetraphosphazene with 1,2-ethanediol.

In this work, the nucleophilic substitution reactions of the cyclotetraphosphazene, tetramer, (1) (N4P4Cl8) with the disodium salt of 1,2-ethanediol in THF solution at different mole ratios were demonstrated. Surprisingly, one double bridged (2) and three ansa derivatives [bis (3), tris (4) and tetrakis (5)] were formed demonstrating two competing pathways in these reactions. The new type cyclotetraphosphazene compounds (2-5) consisting of multiple rings were characterized by elemental analysis, mass spectrometry, 1H and 31P NMR spectroscopy and X-Ray crystallography.

Synthesis of new cyclotriphosphazene derivatives bearing Schiff bases and their thermal and absorbance properties.

In this study, a series of cyclotriphosphazene derivatives containing a Schiff base (3a-3d) were synthesized by the reactions of hexachlorocyclotriphosphazene (1) with bis-aryl Schiff bases ( - ) having different terminal groups (H, F, Cl, and Br). The products ( - ) were characterized by elemental and mass analyses, FT-IR, and H, C, and P NMR spectroscopies. Furthermore, the structure of compound was also determined by X-ray crystallography.

Regiochemical Control in the Substitution Reactions of Cyclotriphosphazene Derivatives with Secondary Amines.

The substitution reactions of the monospiro and geminally disubstituted cyclotriphosphazene derivatives NPClR (R = OCH(CF)CHO (1a), SPh (1b), OCHCHCHO (1c), NHPh (1d), OCHCHCHNH (1e), NHBu (1f)) with two secondary amines (pyrrolidine and dimethylamine) were carried out to investigate geminal or non-geminal directing effects in mixed substituent cyclophosphazenes. The relative amounts of isomeric products, geminal and non-geminal trans or cis, was established quantitatively from the P NMR spectra of the reaction mixtures. Although secondary amines generally follow a non-geminal pathway in the reactions with hexachlorocyclotriphosphazene, in this work, the reactions of two different secondary amines with some NPClR (R = OCHCHCHNH, NHPh, NHBu) derivatives lead to the formation of geminal products.

New Synthetic Approach to Molecular Rods Using Cyclophosphazene-Based Oligospiranes.

A synthetic approach was developed to prepare a new type of highly functionalized inorganic-organic heterocyclic molecular rod (3a and 3b) consisting of cyclophosphazene and carbocyclic units. Single-crystal X-ray diffraction analysis of 3a revealed that the molecular length was ca. 2.

Unexpected Ring Expansion of a Four-Membered Cyclophosphazane.

Nucleophilic substitution reactions of the N(R),N(R)-spiro-bridged octachlorobis(cyclotriphosphazene), N3P3Cl4[N(CH2)5CH3]2N3P3Cl4 (1), with sodium salts of alcohols (1,3-propanediol, 2,2,3,3,4,4-hexafluoro-1,5-pentanediol, and phenol) give ansa products (2-4) via an unexpected rearrangement. These products were characterized by elemental analysis, mass spectrometry, and (1)H and (31)P NMR spectroscopy. The molecular structures of compounds 3 and 4 were also established by X-ray crystallography.