Heteroatom Ring Systems

Heteroatom Ring Systems. Triazadiphosphorines (100) result from cyclocondensation reactions, in the presence of CCI4, of bis(diphenylphosphino)-amine and bifunctional amidines, guanines, isoureas, and isothioureas,  

Derivatives of the diazaphosphorine system (101) can be obtained by treating 3-aminoacrylonitriles or (aminomethylene)malononitriles with 

The former gives in addition the isomeric linear compound R C(N== PCl3)==C(CN)R, which is converted into the diazaphosphorine in the presence of HCl. Primary amine reactions with (101 R = Ph, R = CN) take place rapidly, substituting one chlorine at the phosphorus atom first, then replacing that at carbon before substituting the second chlorine at phosphorus.  

Compounds containing Heteroatom Ring Systems. A four-membered diaza-phosphete (69) is the product from reaction between ammonium chloride 

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Allcock HR (1967) Heteroatom ring systems and polymers. Academic, New York... 

Allcock, H. R. Heteroatom Ring Systems and Polymers Academic Press New York, 1967. 

NMR spectroscopy ( Se, /= 1/2, 7%) is a powerful technique for identifying cyclic selenium molecules, especially the heteroatomic ring systems that contain sulfur or tellurium in addition to selenium, for which several isomers are possible for most compositions (Section 12.1.2). Solutions of monoclinic selenium in CS2 have been shown by high-performance liquid chromatography to form an equilibrium mixture of cyclo-Seg, cyclo-Sey and cyclo-Se6. The Se NMR spectra of such solutions show two singlets that are attributable to cyclo-Seg and cyclo-Se with relative intensities that correspond to a molar ratio of ca 6 No resonance is observed for cyclo-Sey presumably as a result of the fluxional behaviour (pseudorotation) of the seven-membered ring (Section 12.1.2). 

B. Zwanenburg, Synthetic potential of heteroatomic ring systems. Pure Appl. Chem., 71 (1999) 423. 

H. R. Allcock, Heteroatom Ring Systems and Polymers, Academic Press, New York, 1967. R. J. Cotter and M. Matzner, Carhocyclic and Metallorganic Rings, Vol. 13A of Ring-Forming Polymerization, Academic Press, New York, 1969. 

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