Iminophosphorane-substituted proton sponges. Part 5. Structures in the solid state. Correlation between solid state 31P MAS NMR spectra and crystal structures

Abstract

The ³¹P NMR spectra of protonated Iminophosphorane-substituted proton sponges of known crystal structure have been recorded in the solid state under the conditions of magic angle spinning (MAS) and ¹H-decoupling. Variable temperature experiments and a comparison with the averaged ³¹P 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 ³¹P MAS NMR spectroscopy, for compounds which do not yield suitable monocrystals.