Nitrogen triiodide

Stickstofftriiodid

Black brown solid

Fixed

In water decomposition

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Iodstickstoff ( NI3 ), also referred to as Stickstofftriiodid or chemically correct with Iodnitrid, is a highly unstable chemical compound of iodine and nitrogen, which is already at the lowest supply of energy through friction, impact or shock a strongly exothermic reaction (explosion) shows. Stickstofftriiodid belongs to the group of Stickstoffhalogenide.

Due to its instability Iodstickstoff find no practical application as an explosive. However, the synthesis of small quantities is for didactic illustration in the context of chemical education interesting. The dried compound is very sensitive and decomposes in contact or heating immediately with a spectacular bang, which is accompanied by a violet iodine cloud.

Synthesis

In its pure form Iodstickstoff was first synthesized in 1990 of boron nitride and iodine fluoride in trichlorofluoromethane at -30 ° C.

Rather common is the representation by introducing iodine vapor or addition of iodine crystals in a concentrated aqueous ammonia solution. The nitrogen is halogenated (only formal analogy to the hydrocarbons ). This leads to the formation of a usually known as polymeric Iodstickstoff Stickstofftriiodid ammonia adduct NI3 · NH3. This makes black-brown, rhombic crystals, which decompose in water to hydrogen iodide, iodine and ammonia.

The product is highly explosive and must be handled with caution.

Properties

Dry Iodstickstoff decomposes explosively with minimal mechanical action. Even the light touch with a bird feather triggers the explosion. Spontaneous explosions occur. The explosion is always very sharp bang. When dry solid extreme caution. In contrast to the dried solid can work safely with soft damp Iodstickstoff what makes this substance in smaller quantities at a popular chemist prank.

Ammonia adducts

Depending on the temperature and solvent is Iodstickstoff with ammonia the hydrates corresponding differently colored polymeric adducts:

• At temperatures of -30 to -15 ° C precipitated by addition of iodine in a concentrated ammonia solution, a black - brown precipitate of the composition ( NI3 · NH3) n from;
• At -35 to -70 ° C in liquid ammonia produced a green, iridescent, poorly soluble polymer of formula ( NI3 · 3 NH3) n;
• At -75 to -95 ° C, a red precipitate a polymer ( NI3 · 5 NH3) is formed in a 2:1 mixture of chloroform and ammonia n

The two latter adducts can be converted to each other by varying the temperature. All polymers consist of chains of NI4 tetrahedra, which are additionally surrounded by ammonia molecules.