Corrin

Corrin is a heterocyclic compound. It is the parent macrocycle related to the substituted derivative that is found in vitamin B₁₂. Its name reflects that it is the "core" of vitamin B₁₂ (cobalamins).[1]

Corrin

Identifiers
CAS Number	262-76-0
3D model (JSmol)	Interactive image
ChEBI	CHEBI:33221
ChemSpider	16736705
PubChem CID	6438343
UNII	288E04GRMT
CompTox Dashboard (EPA)	DTXSID70893668
InChI InChI=1S/C19H22N4/c1-3-14-10-16-5-7-18(22-16)19-8-6-17(23-19)11-15-4-2-13(21-15)9-12(1)20-14/h9-11,18-19,22H,1-8H2/b12-9-,15-11-,16-10- Key: WUPRCGRRQUZFAB-DEGKJRJSSA-N InChI=1/C19H22N4/c1-3-14-10-16-5-7-18(22-16)19-8-6-17(23-19)11-15-4-2-13(21-15)9-12(1)20-14/h9-11,18-19,22H,1-8H2/b12-9-,15-11-,16-10- Key: WUPRCGRRQUZFAB-DEGKJRJSBL
SMILES N=1C=4CCC=1\C=C2/NC(CC2)C\5CC/C(C=C3\CC/C(=N3)/C=4)=N/5
Properties
Chemical formula	C19H22N4
Molar mass	306.40478
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Coordination chemistry

Upon deprotonation, the corrinoid ring is capable of binding cobalt. In vitamin B₁₂, the resulting complex also features a benzimidazole-derived ligand, and the sixth site on the octahedron serves as the catalytic center.

The corrin ring resembles the porphyrin ring, which occurs in hemoglobin. Both feature four pyrrole-like subunits organized into a ring with a largely conjugated structure of alternating double and single bonds. In contrast to porphyrins, corrins lack one of the carbon groups that link the pyrrole-like units into a fully conjugated structure. With a conjugated system that extends only 3/4 of the way around the ring, and does not include any of the outer edge carbons, corrins have a number of non-conjugated sp³ carbons, making them more flexible than porphyrins and not as flat. A third closely related biological structure, the chlorin ring system found in chlorophyll, is intermediate between porphyrin and corrin, having 20 carbons like the porphyrins and a conjugated structure extending all the way around the central atom, but with only 6 of the 8 edge carbons participating.

Corroles (octadehydrocorrins) are fully aromatic derivatives of corrins.

References

1. Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.