Editing Zwitterion (section)

==Other compounds==
<gallery mode="packed">
File:Zwitterion Structural Formulae V.1.svg|[[Sulfamic acid]] isomers, with the zwitterion (right)
File:Anthranilsäure.svg|[[Anthranilic acid]]
File:EDTA-xtal-2D-skeletal.png|Structure of [[EDTA|H<sub>4</sub>EDTA]]
File:Psilocybin, Kekulé, skeletal formula of canonical psilocybin.svg| [[Psilocybin]]
</gallery>
[[Sulfamic acid]] crystallizes in the zwitterion form.<ref name="Sass">{{ cite journal | first= R. L.|last= Sass |date=1960 | title = A neutron diffraction study on the crystal structure of sulfamic acid | journal = Acta Crystallographica | volume = 13 | issue = 4 | pages = 320–324 | doi = 10.1107/S0365110X60000789 | doi-access = free }}</ref>

In crystals of [[anthranilic acid]] there are two molecules in the [[unit cell]]. One molecule is in the zwitterion form, the other is not.<ref>{{cite journal |last1=Brown |first1=C. J. |last2=Ehrenberg |first2=M. |title=Anthranilic acid, C<sub>7</sub>H<sub>7</sub>NO<sub>2</sub>, by neutron diffraction |journal=Acta Crystallographica C |date=1985 |volume=41 |issue=3 |pages=441–443 |doi=10.1107/S0108270185004206}}</ref>

In the solid state, [[EDTA|H<sub>4</sub>EDTA]] is a zwitterion with two protons having been transferred from carboxylic acid groups to the nitrogen atoms.<ref>{{cite journal |first= Par Michel |last= Cotrait |title= La structure cristalline de l'acide éthylènediamine tétraacétique, EDTA |trans-title=The crystalline structure of ethylenediamine tetraacetic acid, EDTA |year= 1972 |journal= Acta Crystallographica B |volume= 28 |issue= 3 |pages= 781–785 |doi= 10.1107/S056774087200319X}}</ref>

In [[psilocybin]], the proton on the dimethyl amino group is [[lability#chemistry|labile]] and may jump to the phosphate group to form a compound which is not a zwitterion.