Nitrogen triiodide
Encyclopedia
Nitrogen triiodide is the inorganic compound
with the formula N
I
3. It is an extremely sensitive contact explosive
: small quantities explode with a gunpowder-like snap when touched even lightly, releasing a purple cloud of iodine vapor. NI3 has a complex structural chemistry that is difficult to study because of the instability of the derivatives.
in 1990 when it was prepared by an ammonia-free route. Boron nitride
reacts with iodine fluoride
in trichlorofluoromethane
at −30 °C to produce pure NI3 in low yield:
NI3 is pyramidal (C3v molecular symmetry
), as are the other nitrogen trihalides as well as 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 decomposition of NI3 proceeds as follows to give nitrogen gas and iodine:
However, the dry material is a contact explosive, decomposing approximately as follows:
Consistent with this equation, these explosions leave orange-to-purple stains of iodine, which can be removed with sodium thiosulfate
solution. An alternate method of stain removal is to simply allow the iodine time to sublime.
Small amounts of nitrogen triiodide are sometimes synthesized as a demonstration to high school chemistry students or as an act of "chemical magic". To highlight the sensitivity of the compound, it is usually detonated by touching it with a feather but even the slightest air current or other movement can cause detonation
. Nitrogen triiodide is also notable for being the only known chemical explosive that detonates when exposed to alpha particles and nuclear fission
products.
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
with the formula N
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
I
Iodine
Iodine is a chemical element with the symbol I and atomic number 53. The name is pronounced , , or . The name is from the , meaning violet or purple, due to the color of elemental iodine vapor....
3. It is an extremely sensitive contact explosive
Contact explosive
Contact explosive generally refers to any substance that will explode when relatively small quantities of energy are applied to the substance, whether that be heat, light, sound, or physical pressure and even Alpha radiation.Examples include:...
: small quantities explode with a gunpowder-like snap when touched even lightly, releasing a purple cloud of iodine vapor. NI3 has a complex structural chemistry that is difficult to study because of the instability of the derivatives.
Structure of NI3 and its derivatives
Nitrogen triiodide was first characterized by X-ray crystallographyX-ray crystallography
X-ray crystallography is a method of determining the arrangement of atoms within a crystal, in which a beam of X-rays strikes a crystal and causes the beam of light to spread into many specific directions. From the angles and intensities of these diffracted beams, a crystallographer can produce a...
in 1990 when it was prepared by an ammonia-free route. Boron nitride
Boron nitride
Boron nitride is a chemical compound with chemical formula BN, consisting of equal numbers of boron and nitrogen atoms. BN is isoelectronic to a similarly structured carbon lattice and thus exists in various crystalline forms...
reacts with iodine fluoride
Iodine fluoride
Iodine fluoride may refer to:* Iodine monofluoride , IF* Iodine trifluoride , IF3* Iodine pentafluoride , IF5* Iodine heptafluoride , IF7...
in trichlorofluoromethane
Trichlorofluoromethane
Trichlorofluoromethane, also called freon-11, CFC-11, or R-11, is a chlorofluorocarbon. It is a colorless, nearly odorless liquid that boils at about room temperature.- Uses :It was the first widely used refrigerant...
at −30 °C to produce pure NI3 in low yield:
- BN + 3IF → NI3 + BF3
NI3 is pyramidal (C3v molecular symmetry
Molecular symmetry
Molecular symmetry in chemistry describes the symmetry present in molecules and the classification of molecules according to their symmetry. Molecular symmetry is a fundamental concept in chemistry, as it can predict or explain many of a molecule's chemical properties, such as its dipole moment...
), as are the other nitrogen trihalides as well as ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
.
The material that is usually called "nitrogen triiodide" is prepared by the reaction of iodine with ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
. 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
Adduct
An adduct is a product of a direct addition of two or more distinct molecules, resulting in a single reaction product containing all atoms of all components. The resultant is considered a distinct molecular species...
NI3·(NH3). This adduct was first reported by Bernard Courtois
Bernard Courtois
Bernard Courtois, also spelled Barnard Courtois, was a French chemist born in Dijon, France.- Early life :...
in 1812, and its formula was finally determined in 1905 by Oswald Silberrad
Oswald Silberrad
Oswald Silberrad was a British chemist who specialised in explosives, the related field of dye stuffs, and metallurgy.- Life and works :...
. 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.
Decomposition and explosiveness
The instability of NI3 and NI3NH3 can be attributed 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 highly 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 as dynamiteDynamite
Dynamite is an explosive material based on nitroglycerin, initially using diatomaceous earth , or another absorbent substance such as powdered shells, clay, sawdust, or wood pulp. Dynamites using organic materials such as sawdust are less stable and such use has been generally discontinued...
.
The decomposition of NI3 proceeds as follows to give nitrogen gas and iodine:
- 2 NI3 (s) → N2 (g) + 3 I2 (g) (–290 kJ/mol)
However, the dry material is a contact explosive, decomposing approximately as follows:
- 8 NI3NH3 → 5 N2 + 6 NH4I + 9 I2
Consistent with this equation, these explosions leave orange-to-purple stains of iodine, which can be removed with sodium thiosulfate
Sodium thiosulfate
Sodium thiosulfate , also spelled sodium thiosulphate, is a colorless crystalline compound that is more familiar as the pentahydrate, Na2S2O3•5H2O, an efflorescent, monoclinic crystalline substance also called sodium hyposulfite or “hypo.”...
solution. An alternate method of stain removal is to simply allow the iodine time to sublime.
Small amounts of nitrogen triiodide are sometimes synthesized as a demonstration to high school chemistry students or as an act of "chemical magic". To highlight the sensitivity of the compound, it is usually detonated by touching it with a feather but even the slightest air current or other movement can cause detonation
Detonation
Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...
. Nitrogen triiodide is also notable for being the only known chemical explosive that detonates when exposed to alpha particles and nuclear fission
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...
products.