(13C,2H) residual dipolar and indirect spin–spin coupling effects in high-resolution13C 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〉.