NMR crystallography: structure and properties of materials from solid-state nuclear magnetic resonance observables

Bryce, D.L.

doi:10.1107/S2052252517006042

Figure 6
Comparison of the ¹³C CP/MAS spectra of the 1,4-diiodotetrafluorobenzene–2,3,5,6-tetramethylpyrazine cocrystal using (a) ¹H cross polarization and (b) ¹⁹F cross polarization. Dashed lines are added as a guide. The labels `C-F' and `C-I' denote the C atom covalently bonded to fluorine and iodine of the halogen-bond donor, respectively. The label `C-N' denotes the C atom covalently bonded to nitrogen of the halogen-bond acceptor. Cross polarization from the ¹H in the 2,3,5,6-tetramethylpyrazine moiety reveals weak C—F and C—I resonances, while cross polarization from ¹⁹F in 1,4-diiodotetrafluorobenzene shows peaks due to the C—N and methyl C atoms; these experiments confirm that the two components have cocrystallized. From Szell et al. (2017