Understanding the physical properties of the organic-inorganic hybrid NH(CH 3 ) 3 CuCl 3 ·2H 2 O is necessary for its potential applications. Initially, the monoclinic structure of this crystal was discussed via single-crystal X-ray diffraction. Moreover, the previously unknown phase transition temperature was 350 K, as revealed by differential scanning calorimetry and powder X-ray diffraction. Attributed to ferroelasticity, domain walls were observed between the temperatures T c (Low) (223 K) and T c (High) (350 K). Furthermore, changes in chemical shifts for 1 H and 13 C indicated alterations in the molecular environment, whereas a notable decrease in line width was attributed to increased molecular motion freedom. Subsequently, spin-lattice relaxation times ( T 1ρ values) for 1 H and 13 C (indicative of energy transfer) were influenced by tumbling motions. The high activation energy barrier for molecular reorientation was associated with the tumbling motion of methyl groups around the triple symmetry axis. These foundational properties guide the development of efficient organic-inorganic hybrids suitable for practical applications., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)