The solid crystal of tetra-n-butylammonium iodide is in the monoclinic crystal system. It has space groupC2/c. The unit cell has dimensions a=14.2806 b=14.1864 c=19.5951 β=111.149. There are eight formulae in the unit cell (Z=8), which has volume 3702.4 Å3.[1]
The enthalpy of formation ΔfH0 of tetra-n-butylammonium iodide is −499 kJ/mol, which is lower than that for the bromide or chloride (−540, −564 kJ/mol).[2]
At lower temperatures with water tetra-n-butylammonium iodide forms a clathrate hydrate.[2] The tetra-n-butylammonium cation is large and hydrophobic. The absolute enthalpy of hydration (from gas phase) is −260 kJ/mol.[2]
The He(I) photoelectron spectrum of tetra-n-butylammonium iodide contains a peak at 11 eV due to the tetra-n-butylammonium cation, and at 7 and 8 eV due to iodide.[3]
^Prukała, Wiesław; Marciniec, Bogdan; Kubicki, Maciej (28 February 2007). "Tetra-n-butylammonium iodide: a space-group revision". Acta Crystallographica Section E. 63 (3): o1464 –o1466. Bibcode:2007AcCrE..63O1464P. doi:10.1107/S1600536807008446.
^ abcNagano, Yatsuhisa; Mizuno, Hideki; Sakiyama, Minoru; Fujiwara, Tadayuki; Kondo, Yasuhiko (March 1991). "Hydration enthalpy of tetra-n-butylammonium ion". The Journal of Physical Chemistry. 95 (6): 2536–2540. doi:10.1021/j100159a079.
^Ballard, R.E.; Jones, Jimmy; Sutherland, Elizabeth (December 1984). "He(I) photoelectron spectrum of tetra-N-butylammonium iodide and bromide in solution. The effects of surface activity". Chemical Physics Letters. 112 (4): 310–312. Bibcode:1984CPL...112..310B. doi:10.1016/0009-2614(84)85747-4.