Nitrogen triiodide

Names

IUPAC name

Triiodoamine

Other names

Nitrogen iodide
Ammonia triiodide
Triiodine nitride
Triiodine mononitride
Triiodamine

Identifiers

CAS Number

13444-85-4^Y

3D model (Jmol)

55511^Y

InChI=1S/I3N/c1-4(2)3^Y

Key: FZIONDGWZAKCEX-UHFFFAOYSA-N^Y
InChI=1/I3N/c1-4(2)3

Key: FZIONDGWZAKCEX-UHFFFAOYAL

SMILES

IN(I)I

Properties

Chemical formula

NI₃

Molar mass

394.719 g/mol

Appearance

red solid

Boiling point

sublimes at −20 °C

Solubility in water

Insoluble

Solubility

organic solvents, such as diethyl ether

Hazards

Main hazards

Extremely explosive

NFPA 704

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

(what is ^YN ?)

Infobox references

Nitrogen triiodide is the inorganic compound with the formula N I₃. It is an extremely sensitive contact explosive: small quantities explode with a loud, sharp snap when touched even lightly, releasing a purple cloud of iodine vapor; it can even be detonated by alpha radiation. NI₃ has a complex structural chemistry that is difficult to study because of the instability of the derivatives.

Nitrogen triiodide was first characterized by Raman spectroscopy in 1990 when it was prepared by an ammonia-free route. Boron nitride reacts with iodine monofluoride in trichlorofluoromethane at −30 °C to produce pure NI₃ in low yield:

NI₃ is pyramidal (C_3vmolecular symmetry), as are the other nitrogen trihalides and ammonia.

The material that is usually called "nitrogen triiodide" is prepared by the reaction of iodine with ammonia. When this reaction is conducted at low temperatures in anhydrous ammonia, the initial product is NI₃ · (NH₃)₅, but this material loses some ammonia upon warming to give the 1:1 adduct NI₃ · NH₃. This adduct was first reported by Bernard Courtois in 1812, and its formula was finally determined in 1905 by Oswald Silberrad. Its solid state structure consists of chains of -NI₂-I-NI₂-I-NI₂-I-... Ammonia molecules are situated between the chains. When kept cold in the dark and damp with ammonia, NI₃ · NH₃ is stable.

The instability of NI₃ and NI₃ · NH₃ can be attributed to the large steric strain caused by the three large iodine atoms being held in proximity to each other around the relatively tiny nitrogen atom. This results in a very low activation energy for its decomposition, a reaction made even more favorable due to the great stability of N₂. Nitrogen triiodide has no practical commercial value due to its extreme shock sensitivity, making it impossible to store, transport, and utilize for controlled explosions. Whereas pure nitroglycerin is also greatly shock-sensitive (although not nearly as much so as nitrogen triiodide, which can be set off with the touch of a feather) and powerful, it was only due to phlegmatizers that its shock sensitivity was reduced and it became safer to handle and transport in the form of dynamite.

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