# Iodine nitrogen

Structural formula
General
Surname Iodine nitrogen
other names

Nitrogen triiodide

Molecular formula NI 3
Brief description

black-brown solid

External identifiers / databases
 CAS number 13444-85-4 (NI 3 ) 14014-86-9 (NI 3 ⋅ NH 3 ) 15823-38-8 (NI 3 ⋅ 3 NH 3 ) PubChem 61603 ChemSpider 55511 Wikidata Q407716
properties
Molar mass 394.7 g mol −1
Physical state

firmly

solubility

decomposes in water

safety instructions
GHS hazard labeling
no classification available
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Iodine nitrogen (NI 3 ), also known as nitrogen triiodide or chemically correct with iodine nitride , is an extremely labile chemical compound of iodine and nitrogen , which shows a strongly exothermic reaction ( explosion ) even with the slightest input of energy due to friction, impact or vibration .

Nitrogen triiodide belongs to the group of nitrogen halides .

## synthesis

In pure form, iodine nitrogen was first synthesized in 1990 from boron nitride and iodine fluoride at −30 ° C in trichlorofluoromethane .

${\ displaystyle \ mathrm {BN + 3 \ IF \ {\ xrightarrow {-30 \, ^ {\ circ} \ mathrm {C}}} \ NI_ {3} + BF_ {3}}}$

It is more common to display it by introducing iodine vapor or adding iodine crystals to a concentrated aqueous ammonia solution. The nitrogen is halogenated (only formally analogous to the hydrocarbons ). This leads to the formation of a polymeric nitrogen triiodide-ammonia adduct, usually referred to as iodine-nitrogen, NI 3 · NH 3 . This forms black-brown, rhombic crystals which decompose in water to form hydrogen iodide , iodine and ammonia.

${\ displaystyle \ mathrm {3 \ I_ {2} +5 \ NH_ {3} \ longrightarrow 3 \ NH_ {4} I + NH_ {3} \ cdot NI_ {3 (s)} \ downarrow}}$

The product is highly explosive and must be handled with the necessary care.

## properties

Dry iodine nitrogen decomposes explosively with the slightest mechanical impact. Even a light touch with a bird's feather triggers the explosion. Spontaneous explosions also occur. The explosion always occurs with a very sharp bang. Great care must be taken with the dry solid. In contrast to the dried solid, it is safe to work with alcohol-moist iodine nitrogen, which makes this substance a popular prank for chemists in smaller quantities.

${\ displaystyle \ mathrm {2 \ NI_ {3 (s)} \ {\ xrightarrow {impact, \ friction}} \ N_ {2 (g)} + 3 \ I_ {2 (g)}}}$

Depending on the temperature and solvent, iodine-nitrogen forms differently colored polymeric adducts with ammonia corresponding to the hydrates :

• at temperatures from −30 to −15 ° C, a black-brown precipitate with the composition (NI 3  · NH 3 ) n is formed by adding iodine to a concentrated ammonia solution ;
• at −35 to −70 ° C a green, iridescent, poorly soluble polymer of the formula (NI 3  · 3 NH 3 ) n is formed in liquid ammonia ;
• At −75 to −95 ° C, a red precipitate of a polymer (NI 3  · 5 NH 3 ) n forms in a 2: 1 mixture of chloroform and ammonia .

The latter two adducts can be converted into one another by varying the temperature. All polymers consist of chains of NI 4 - tetrahedra which are additionally surrounded by ammonia molecules.

## use

Because of its instability, iodine nitrogen has no practical use as an explosive . The synthesis of very small quantities is interesting for didactic illustration in the context of chemistry lessons, but is explicitly prohibited in Germany's schools. The dried compound is very delicate and immediately disintegrates when touched or heated with a spectacular bang accompanied by a purple cloud of iodine.