I found the structural formula of Benzenediazonium chloride written on a website:

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I believe that the Cl- ion is stabilizing the N+ ion.

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So, shouldn't the structural formula be written like the above instead?

  • 1
    $\begingroup$ Note that the topic has two levels - a preferred formal one and structural one. For the latter, I am not aware of forming ionic pairs here. $\endgroup$
    – Poutnik
    Jun 21 at 6:32

2 Answers 2


With respect to the point of your question, both ion placements are acceptable for the specified form of the salt's structural formula. From section GR-7.2 Positioning of components [1, p. 383] (emphasis mine):

The various components of a salt may be positioned relative to each other in one of two ways. If one of the components consists of a single atom, it may be “paired up” with an oppositely charged atom in a larger component, with the positioning of the larger fragment determined by other considerations as discussed in GR-3. The fragments should be positioned as if there were a single bond between the cationic and anionic centers, even if this requires that the cation be drawn on the right side of the anion. The positioning of the smaller fragment will then usually be determined according to other recommendations (that straight chains should not have arbitrary bends in them, for example).

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Alternatively, the components of a salt may be depicted next to each other. This positioning is acceptable for single-atom components, and preferred for larger ones. If the components are of similar size, positively charged components should preferably be positioned to the left of negatively charged ones; if they are significantly different in size, the larger components should be positioned to the left of the smaller ones.

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  1. Negative charge should be depicted with superscripted minus $(\ce{Cl-}),$ not en dash $(\ce{Cl^\text{-}}).$
  2. Although being acceptable, a circle is rarely used for the depiction of aromatic systems in publications beyond introductory level chemistry.
  3. Chemical names are common nouns and inherit the capitalization rules: do not capitalize chemical names in the middle of the sentence.
  4. An inline semistructural formula of benzenediazonium chloride could be $\ce{Ph-N2+ Cl-}.$
  5. Even in the crystal structure ([2]; CSD Entry: BZDIZC) $\ce{Cl-}$ anion is equally distanced from nitrogen atoms in diazonium (an isosceles triangle with the legs of ~3.55 Å or ~3.23 Å): Crystal structure of benzenediazonium chloride


  1. Brecher, J. Graphical Representation Standards for Chemical Structure Diagrams (IUPAC Recommendations 2008). Pure Appl. Chem. 2009, 80 (2), 277–410. DOI: 10.1351/pac200880020277. (Free Access)
  2. Rømming, Chr.; Karvonen, P.; Holm, A.; Nielsen, P. H.; Munch-Petersen, J. The Structure of Benzene Diazonium Chloride. Acta Chem. Scand. 1963, 17, 1444–1454. DOI: 10.3891/acta.chem.scand.17-1444. (Free Access)

You are right. But it is not always possible to print this formula with $\ce{Cl-}$ ion UNDER the diazo line. It depends on the programs available on your computer, specially if you replace the benzene ring by the formula $\ce{C6H5}$, and if you want to type it on one line in a text.


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