What is the difference between the structure of nitrito-O and nitrito-N?

I am preparing for chemistry olympiad and I am stuck nitrito-*O* and nitrito-*N*. Can anyone explain difference between the structure of nitrito-*O* and nitrito-*N* or point a resource which is suitable for a beginner?




The last letter of nitrite-*O* and nitrite-*N* depicts the atom which is attached to the other atom. This phenomenon is called [linkage isomerism](https://en.wikipedia.org/wiki/Linkage_isomerism) and is an important concept in both organic and inorganic chemistry.


### Inorganic chemistry


[![pentaamminenitrito-N-cobalt(III)](https://i.stack.imgur.com/6Jy88.png)](https://i.stack.imgur.com/6Jy88.png)


This complex exhibits linkage isomerism which results in two possible ways of attachment of ligand to the central atom. First one, the $\ce{NO2}$ ligates with (attaches to) the central atom through the **nitrogen atom** and thus is called pentaammine**nitrito-*N***-cobalt(III) chloride and the second one, $\ce{NO2}$ ligates with the central atom through the **oxygen atom** and thus is called pentaammine**nitrito-*O***-cobalt(III) chloride. In this case, $\ce{NO2}$ is called ambident ligand and is represented as **nitrito-κ-*N*** and **nitrito-κ-*O***, replacing the old system of trivial names such as nitro and nitroso.


### Organic chemistry


Alkyl nitrite forms two isomers: $\ce{RNO2}$ (called alkyl **nitrite-*N***) and $\ce{R-O-N=O}$ (called alkyl **nitrite-*O***).For preparation of these two isomers, see [Reaction of an alkyl halide with silver nitrite](https://chemistry.stackexchange.com/questions/50188).


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