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Azanes/ˌæzeɪns/ are acyclic,saturated hydronitrogens, which means that they consist only ofhydrogen andnitrogen atoms and all bonds aresingle bonds. They are thereforepnictogen hydrides. Becausecyclic hydronitrogens are excluded by definition, the azanes comprise ahomologous series of inorganic compounds with the general chemical formulaN
nH
n+2.
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. N2-azane).
The simplest possible azane (the parent molecule) isammonia,NH
3. 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 significantbiological activity. Azanes can be viewed as a more biologically active or reactive portion (functional groups) of the molecule, which can be hung upon molecular trees.
Saturated hydronitrogens can be:
According toIUPAC 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 areacyclic (i.e., having no loops). They also have single covalent bonds between their nitrogens.
Azanes with more than three nitrogen atoms can be arranged in various different ways, formingstructural isomers. 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 bechiral. In addition to these isomers, the chain of nitrogen atoms may form one or more loops. Such compounds are called cycloazanes.
The IUPAC nomenclature systematically naming nitrogen compounds by identifying hydronitrogen chains, analogous to thealkane 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.[1]
Straight-chain azanes are sometimes indicated by the prefixn- (fornormal) 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:
Azanes with three or more nitrogen atoms are named by adding thesuffix -azane to the appropriatenumerical multiplier prefix. Hence,triazane,N
3H
5; tetrazane or tetraazane,N
4H
6; pentazane or pentaazane,N
5H
7; hexazane or hexaazane,N
6H
8; etc. The prefix is generally Greek, with the exceptions of nonaazane which has aLatin prefix, and undecaazane and tridecaazane which have mixed-language prefixes.
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 to the azanes are a homologous series offunctional groups,side-chains, orradicals with the general chemical formulaN
nH
n+1. Examples includeazanyl (NH
2) and hydrazinyl. This group is generally abbreviated with the symbol N.[citation needed]