Cation dynamics by 1 H and 13 C MAS NMR in hybrid organic-inorganic (CH 3 CH 2 NH 3 ) 2 CuCl 4 .

To understand the dynamics of the cation in layered perovskite-type (CH 3 CH 2 NH 3 ) 2 CuCl 4 , the temperature-dependent chemical shifts and spin-lattice relaxation times T 1ρ in the rotating frame have been measured using 1 H magic angle spinning nuclear magnetic resonance (MAS NMR) and 13 C cross-polarization (CP)/MAS NMR techniques. Each proton and carbon in the (CH 3 CH 2 NH 3 ) + cation is distinguished in MAS NMR spectra. The Bloembergen-Purcell-Pound (BPP) curves for 1 H T 1ρ in CH 3 CH 2 and NH 3 , and for the 13 C T 1ρ in CH 3 and CH 2 are revealed to have minima at low temperatures. This implies that the curves represent the CH 3 and NH 3 + rotational motions. The amplitude of the cationic motion is enhanced at the C-end, that is, the N-end of the organic cation is fixed to the inorganic layer through N-H⋯Cl hydrogen bonds, and T 1ρ becomes short with larger-amplitude molecular motions.