Chapter 16: Locating Hydrogen Atoms Using Fast-MAS Solid-state NMR and microED

Methods to locate hydrogen atoms in solids using fast-MAS solid-state NMR and their application for atomic-resolution structural studies are summarized in this chapter. The location of H atoms as well as the inter-atomic distances involving H atoms can be accurately determined by experimentally measuring hetero- and homonuclear dipolar couplings involving H atoms. Heteronuclear dipolar couplings can be determined by monitoring the evolution of magnetization under the influence of heteronuclear couplings or from the build-up of the dipolar-mediated magnetization transfer under fast-MAS, while the magnetization exchange build-up curves can also be utilized to determine ¹H–¹H homonuclear dipolar couplings. In this chapter, a combination of microED and solid-state NMR experiments is also introduced to obtain the crystal structure from nano- to microcrystals. The crystalline structure, including hydrogen atom positions, was validated by solid-state NMR in the framework of NMR crystallography.