(13C, 2H) residual dipolar and indirect spin–spin coupling effects in high-resolution 13C nuclear magnetic resonance spectra of solids

Abstract

We report high-resolution solid-state ¹³C NMR spectra of urea and thiourea inclusion compounds containing deuteriated guest molecules. The spectra (recorded under conditions of magic-angle sample spinning and high-power ¹H decoupling at several magnetic fields from 4.7 to 11.7 T) for CD, CD₂ and CD₃ groups are triplets, pentets and heptets, respectively. These multiplets arise from the effects of residual dipolar interaction and indirect spin–spin coupling between ¹³C and ²H. A full analysis of these lineshapes is presented, and the effect of molecular motion is discussed. It is shown that the ¹³C NMR lineshape for deuteriated materials which are in a rapid motion regime (with respect to the ²H NMR timescale) can be rationalized by considering the motionally averaged ²H quadrupole coupling constant 〈χ〉.