Isolation and Characterization of Nongeminal Cyclic Methylphenylphosphazene Tetramers

• Published in: Journal of the American Chemical Society 2003-12, Vol.125 (50), p.15537-15542
• Main Authors: Jung, June-Ho, Pomeroy, Julia C, Zhang, Hongming, Wisian-Neilson, Patty
• Format: Article
• Language: English
• Subjects: Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Organic compounds; Organometalloidal and organometallic compounds; Physics; Single-crystal and powder diffraction; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; X-ray diffraction and scattering
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0374168

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.