Abstract: | 31P Cross-polarization magic-angle spinning nuclear magnetic resonance (CP-MAS NMR) spectra of eight monophospha-λ5-azenes were measured at room temperature. Three of these compounds, with 2-OH substituents, are in principle capable of taking part in the equilibrium process. However, only the open form, tautomer A, is found in the present study. 15N CP-MAS NMR spectra support the results. The most shielded component of the 31P chemical shift tensor lies in the direction of the P=N bond. |