Nitrogen Triiodide Ammoniate
Bobby Deimler
Department of Chemistry & Physics,
Georgia College and State University,
Milledgeville, GA 31033
8/26/08
Abstract: This report documents the creation and detonation of a Nitrogen Triiodide
Ammoniate Compound. This compound was created in order to observe its physical
characteristics as well as to explore the way in which Nitrogen reacts with halogen
compounds specifically that of Iodine. Nitrogen Triiodide Ammoniate was created using
iodine and ammonia. This reaction created light colored crystals that detonated upon
agitation. From this process it was concluded that this compound exhibits unique
chemical and physical properties due to its Nitrogen-Halogen nature.
Introduction: Nitrogen is a compound that has many different uses in our daily lives.
Some of these include fillers in light bulbs, in the air that we breathe, and in our
fertilizers. Nitrogen has more potent uses as well including that of explosives and rocket
fuel. What is it about Nitrogen that makes it so potent? This is after all the same
compound that helps the food grow in a farmer’s field. The answer to this has to do with
the type of bonds that are formed when pure Nitrogen, N2, interacts with other
compounds. The following basic reaction is initiated between Iodine and concentrated
Ammonia (Fig. 1).
3I2 + NH3  NI3 * NH3 + 3HI
(Fig. 1)
In this reaction the nitrogen in the ammonia reacts with the iodine in order to form both a
NI3 * NH3 and HI compound. Ammonia is used as a reactant in this experiment because
most haloamines, like this Triiodide, are derivatives of ammonia or another kind of
amine.1 These liquid amines have the advantage of a lower melting point which normally
meets the temperature condition necessary for the reaction.1The HI compound that is
formed is held together by electrostatic forces that are formed between the highly
negative Iodine atom and the positive hydrogen atoms. The other compound formed in
this reaction is Nitrogen Triiodide Ammoniate or NI3 * NH3. This is the compound that
the experiment is attempting to create. In this structure the nitrogen atom is holding the
iodine atoms to itself by very weak single bonds. (Fig 2)
I
|
N
/
I
(Fig. 2)
\
I
Nitrogen tends to form weak single bonds with an oxidizing agents such as oxygen,
halogens, or other nitrogen atoms.2 When this compound is a liquid, the ammonia is still
interacting with the nitrogen triiode structure. This is very important because the
ammonia helps to stabilize the structure allowing for easier transport and safer handling.
This stability is best described by Tudela when he states, “…one NH3 molecule is
attached by a weaker bond to alternate nonbridging iodine atoms along the chain.”3 From
this it can be seen that the ammonia acts as a stabilizer between the iodine atoms weakly
bonding between two units to keep them in a more compatible configuration. It is not
until the ammonia is allowed to evaporate and the solid is formed that this compound
becomes a hazard. In the absence of the stabilizing ammonia, the only thing holding the
structure together is the weak nitrogen bonds. Since, nitrogen is a smaller element it tends
to form smaller bonds relative to its size. This would mean that the smaller nitrogen
would be attempting to hold three much larger iodine atoms in its proximity by fairly
weak bonds. Not only would one have to be concerned with the fact that the bonds are
weak, but also how all three larger iodine atoms could be easily arranged in such a small
area. This would be similar to trying to link three bowling balls to a single golf ball using
short lengths of yarn. Even though the golf ball is able to hold the bowling balls to itself
it is a very weak item that is holding them together. It would also be immensely difficult
to try and arrange the bowling balls so that they all fit in a stable pattern within the
general area surrounding the golf ball. At this point the compound is only waiting for an
excuse to break the bonds. Any force whatsoever, is enough to cause the bonds to rupture
with explosive force. This process is what causes the explosion described in this report.
Experimental: To begin this experiment 105.7 mg of Iodine was weighed on an analytic
balance and placed in a 10 mL beaker. To this beaker both 1 mL of concentrated
ammonia and a magnetic stir bar were added. The solution was then placed on a magnetic
plate and allowed to stir for five minutes. Afterwards, this solution was poured on several
layers of filter paper and allowed to dry for one hour. At the conclusion of this hour
crystals were formed on the paper. These crystals were then detonated by lightly touching
them with a metal rod.
Results/Discussion/Data: This experiment was designed in order to show the chemical
and physical properties of Nitrogen Triiodide Ammoniate. During the course of this
experiment several key characteristics were observed that are mainly attributed to this
compound. When the reactants were combined and agitated they created a dark brown
solution. This was a positive sign because the crystals that we wished to form were
reported to be a similar color in the literature. When this solution was poured onto the
filter paper it appeared to be a completely liquid solution with no solid or semi-solid
particles in it. This observation may have been due to the fact that the solution had not
had enough time unagitated to allow the solid particles to form out of solution. Another
reason for this could be that at this point the solution had not formed particles that were
large enough to be seen with the naked eye. Regardless of the reason after the solution
was allowed to dry it was observed that they did form crystals that were yellow to white
in color. These crystals demonstrated their true nature when a ruler disturbed them. As
soon as the ruler came into contact with the paper the crystals let off a loud noise and a
small cloud of red gas. This red gas is most likely attributed to the iodine atoms that are
released by the rupture of the weak nitrogen bonds. This is very characteristic of this
Triiodide compound and allows the conclusion that this was made in this experiment.
Upon initial observation this may seem like a rather superfluous experiment in which the
goal is to see an explosion. On the contrary this is an experiment that holds a fair amount
of significance. This experiment can be used to demonstrate several concepts that are
relevant in the scientific learning community. The first concept that this experiment
demonstrates is chemical safety. This experiment helps to expose students to compounds
that may be explosive or exhibit other dangerous characteristics. Knowing how to
properly handle these materials will make future lab endeavors more secure. The other
reason is that this experiment demonstrates the chemical characteristics of nitrogen
compounds in a way that is interesting. Its explosive presentation grabs the attention of
both the chemistry and non-chemistry oriented persons. It helps to solidify the
experience of both the experiment and its explanation within their memory.
Conclusion: This experiment can be counted as a success because enough sample was
created in order to observe the properties of the compound. From this experiment
knowledge has been gained about the chemical and physical properties of Nitrogen
Triiodide Ammoniate as well as some ways in which Nitrogen compounds interact with
halogens. A continuation of this experiment will ascertain how testing larger and smaller
quantities of the reactants could determine the limits of the reaction. Another way in
which the lab could continue to evolve would be to test other Nitrogen-Halogen
compounds in order to see if they have similar properties to that of those used in this
experiment.
References:
[1] Jander, Jochen. Pure & Appl. Chem. 1977, vol, 49.
[2] Szafran, Zvi, Pike, Ronald M., Singh, Mono M. Microscale Inorganic Chemistry: A
Comprehensive Laboratory Experience; 1st Ed.; J. Wiley: 1991; pp. 199-201
[3] Tudela, David. J. Chem. Ed. 2002, vol. 79.
Acknowledgements:
I would like to acknowledge my lab partner Greg Pittman for his help in the execution of
the experiment.