# Is chlorine the central atom in NOCl?

We've been told that the in the structure of $\ce{NOCl}$ the central atom is $\ce{Cl}$ (rather than $\ce{N}$) due to some exception.

Looking up on internet I could not find anything to support this. I would like to know if it really exists in such a state due to some exception. If yes, what is that exception.

• – Nilay Ghosh Sep 20 '17 at 11:35
• @Tyberius I don’t quite see how the structure of an inorganic molecule has to do with that of hypochlorite … – Jan Sep 27 '17 at 8:49

Wikipedia gives a structure with a central nitrogen atom:

The nitrogen atom (blue, using the standard color scheme) can form all three covalent bonds without building up an excess positive or negative charge, and so is favored in the central position through which all three bonds pass.

The only situation where I can imagine $\ce{N-Cl-O}$ bond is N-perchloryls ($\ce{R2NClO3}$); from [1]:

The perchlorylamines were obtained as carbon tetrachloride solutions, with no impurities detectable by nmr. Thus piperidine, diethylamine, and dipentylamine gave N-perchlorylpiperidine, N-perchloryldiethylamine, and N-perchloryldipentylamine, respectively. [...] $$\ce{2R2NH + Cl2O7 ->[CCl4] R2\color{red}{NClO3} + R2NH2+ClO4-}$$

There are only few coordination compounds with amidoperchlorate group, e.g. $\ce{KH\color{red}{NClO3}}$ and catena(aqua-bis($\mu_2$-(N-cyclohexylamidoperchlorate)-silver(I))) $\ce{AgC6H11\color{red}{NClO3} * 0.5 H2O}$ [2]; crystal structure of the latter is shown below (hydrogen atoms are omitted, numbers show interatomic distances in Å):

$\color{#909090}{\Large\bullet}~\ce{C}$; $\color{#3050F8}{\Large\bullet}~\ce{N}$; $\color{#FF0D0D}{\Large\bullet}~\ce{O}$; $\color{#1FF01F}{\Large\bullet}~\ce{Cl}$; $\color{#C0C0C0}{\Large\bullet}~\ce{Ag}$.

### References

1. Beard, C. D.; Baum, K. J. Am. Chem. Soc. 1974, 96 (10), 3237–3239 DOI: 10.1021/ja00817a034.
2. Pritzkow, H. Zeitschrift für Naturforschung B 1976, 31 (9), 1170–1174 DOI: 10.1515/znb-1976-0903. (In German, free access)