Azanes are acyclic,
saturated hydronitrogens, which means that they consist only of
hydrogen
Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...
and
nitrogen
Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...
atoms and all bonds are
single bond
In chemistry, a single bond is a chemical bond between two atoms involving two valence electrons. That is, the atoms share one pair of electrons where the bond forms. Therefore, a single bond is a type of covalent bond. When shared, each of th ...
s. They are therefore
pnictogen hydride
Pnictogen hydrides or hydrogen pnictides are binary compounds of hydrogen with pnictogen ( or ; from "to choke" and -gen, "generator") atoms (elements of group 15: nitrogen, phosphorus, arsenic, antimony, bismuth, and moscovium) covalently bonded ...
s. Because
cyclic hydronitrogens are excluded by definition, the azanes comprise a
homologous series
In organic chemistry, a homologous series is a sequence of compounds with the same functional group and similar chemical properties in which the members of the series differ by the number of repeating units they contain. This can be the length of ...
of inorganic compounds with the general chemical formula .
Each nitrogen atom has three bonds (either N-H or N-N bonds), and each hydrogen atom is joined to a nitrogen atom (H-N bonds). A series of linked nitrogen atoms is known as the nitrogen skeleton or nitrogen backbone. The number of nitrogen atoms is used to define the size of the azane (e.g. N
2-azane).
The simplest possible azane (the parent molecule) is
ammonia
Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
, . There is no limit to the number of nitrogen atoms that can be linked together, the only limitation being that the molecule is acyclic, is saturated, and is a hydronitrogen.
Azanes are reactive and have significant
biological activity
In pharmacology, biological activity or pharmacological activity describes the beneficial or adverse effects of a drug on living matter. When a drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or ...
. Azanes can be viewed as a more biologically active or reactive portion (
functional groups
In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...
) of the molecule, which can be hung upon molecular trees.
Structure classification
Saturated hydronitrogens can be:
* linear (general formula ) wherein the nitrogen atoms are joined in a snakelike structure
* branched (general formula , ''n'' > 3) wherein the nitrogen backbone splits off in one or more directions
*
cyclic (general formula , ''n'' > 2) wherein the nitrogen backbone is linked so as to form a loop.
According to
IUPAC
The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
definitions, the former two are azanes, whereas the third group is called cycloazanes. Saturated hydronitrogens can also combine any of the linear, cyclic (e.g. polycyclic), and branching structures, and they are still azanes (no general formula) as long as they are
acyclic (i.e., having no loops). They also have single covalent bonds between their nitrogens.
Isomerism
Azanes with more than three nitrogen atoms can be arranged in various different ways, forming
structural isomer
In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a compound is a compound that contains the same number and type of atoms, but with a different connectivity (i.e. arrangement of bonds) between them. The ...
s. The simplest isomer of an azane is the one in which the nitrogen atoms are arranged in a single chain with no branches. This isomer is sometimes called the n-isomer (n for "normal", although it is not necessarily the most common). However the chain of nitrogen atoms may also be branched at one or more points. The number of possible isomers increases rapidly with the number of nitrogen atoms.
Due to the low energy of inversion, unsubstituted branched azanes cannot be
chiral
Chirality () is a property of asymmetry important in several branches of science. The word ''chirality'' is derived from the Greek language, Greek (''kheir''), "hand", a familiar chiral object.
An object or a system is ''chiral'' if it is dist ...
. In addition to these isomers, the chain of nitrogen atoms may form one or more loops. Such compounds are called cycloazanes.
Nomenclature
The IUPAC nomenclature systematically naming nitrogen compounds by identifying hydronitrogen chains, analogous to the
alkane nomenclature. Unbranched, saturated hydronitrogen chains are named with a Greek numerical prefix for the number of nitrogens and the suffix "-azane" for hydronitrogens with single bonds, or "-azene" for those with double bonds.
[Note that "-yne", which would be used for those with triple bonds, is absent because the only member of that series, N2, is not a hydronitrogen.]
Linear azanes
Straight-chain azanes are sometimes indicated by the prefix ''n''- (for ''normal'') where a non-linear isomer exists. Although this is not strictly necessary, the usage is common in cases where there is an important difference in properties between the straight-chain and branched-chain isomers.
The members of the series (in terms of number of nitrogen atoms) are named as follows:
:
azane (or ammonia), NH
3 - one nitrogen and three hydrogen
:
diazane (or hydrazine), - two nitrogen and four hydrogen
:
triazane
Triazane is an inorganic compound with the chemical formula or . Triazane is the third simplest acyclic azane after ammonia and hydrazine. It can be synthesized from hydrazine but is unstable and cannot be isolated in the free base form, only a ...
, - three nitrogen and five hydrogen
Azanes with three or more nitrogen atoms are named by adding the
suffix
In linguistics, a suffix is an affix which is placed after the stem of a word. Common examples are case endings, which indicate the grammatical case of nouns and adjectives, and verb endings, which form the conjugation of verbs. Suffixes can ca ...
-azane to the appropriate
numerical multiplier prefix. Hence,
triazane
Triazane is an inorganic compound with the chemical formula or . Triazane is the third simplest acyclic azane after ammonia and hydrazine. It can be synthesized from hydrazine but is unstable and cannot be isolated in the free base form, only a ...
, ; tetrazane or tetraazane, ; pentazane or pentaazane, ; hexazane or hexaazane, ; etc. The prefix is generally Greek, with the exceptions of nonaazane which has a
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
prefix, and undecaazane and tridecaazane which have mixed-language prefixes.
Hazards
Ammonia is explosive when mixed with air (15 – 25%). Other lower azanes can also form explosive mixtures with air. The lighter liquid azanes are highly flammable; this risk increases with the length of the nitrogen chain. One consideration for detection and risk control is that ammonia is lighter than air, creating the possibility of accumulation on ceilings.
Related and derived hydronitrogens
Related to the azanes are a homologous series of
functional group
In organic chemistry, a functional group is any substituent or moiety (chemistry), moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions r ...
s,
side-chains, or
radicals with the general chemical formula . Examples include
azanyl () and hydrazinyl. This group is generally abbreviated with the symbol N.
References
{{Hydrides by group
Inorganic compounds
Nitrogen hydrides