Tetra-n-butylammonium iodide: a space-group revision

The crystal structure of tetra-n-butylammonium iodide, C₁₆H₃₆N⁺·I^-, has been redetermined at room temperature and at 100 (1) K. In the low-quality (R = 0.142) room-temperature determination by Wang, Habenschuss, Xenopoulos & Wunderlich [Mol. Cryst. Liq. Cryst. Sci. Technol. Sect. A (1995), 264, 115-129], this structure was described as crystallizing in the space group C2 with Z' = 2. Our results prove that the correct space group is C2/c (with the same unit-cell parameters as in the original determination) at both temperatures. In the crystal structure, the iodide anions fill the voids in the grid-like cationic structure. Weak C—H⋯I interactions (eight per anion) strengthen this packing.