Rotary resonance recoupling of 13C−1H dipolar interactions in magic angle spinning 13C NMR of dynamic solids

Rotary resonance recoupling of heteronuclear 13C−1H dipolar interactions in magic angle spinning solid state 13C NMR spectra (recorded under conditions of 1H decoupling at frequency ν1 and magic angle spinning at frequency νr) has been studied for three examples of molecular solids (adamantane, ferrocene and hexamethylbenzene) in which substantial molecular motion is known to occur. It is shown that when rotary resonance conditions are satisfied (i.e. ν1/νr=n, for n=1 or 2), the recoupling can lead to motionally averaged Pake-like powder patterns from which information on 13C−1H internuclear distances and/or molecular motion can be derived.