IMINOPHOSPHORANE-SUBSTITUTED PROTON SPONGES .5. STRUCTURES IN THE SOLID-STATE - CORRELATION BETWEEN SOLID-STATE P-31 MAS NMR-SPECTRA AND CRYSTAL-STRUCTURES

The P-31 NMR spectra of protonated im inophosphorane-substituted proton sponges of known crystal structure have been recorded in the solid state under the conditions of magic angle spinning (MAS) and H-1-decoupling. Variable temperature experiments and a comparison with the averaged P-31 chemical shifts in solution show that no proton transfer occurs in the crystal, even when strong intramolecular hydrogen bonds are present. Good agreement between the NMR results and the X-ray structures gives weight to structural predictions based on solid state P-31 MAS NMR spectroscopy, for compounds which do not yield suitable monocrystals.