Corrin

Corrin
Identifiers
CAS number	262-76-0
PubChem	6438343
SMILES	C1CC2=NC1C3CCC(=N3)C=C4CCC(=N4)C=C5CCC(=C2)N5
InChI	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-
Properties
Molecular formula	C19H22N4
Molar mass	306.40478
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Corrin is a macrocycle related to the porphyrin ring in hemoglobin, consisting of 4 pyrrole subunits, joined on opposite sides by a C-CH₃ methylene link, on one side by a C-H methylene link, and with the two of the pyrroles joined directly. Compared to a porphyrin, it is missing a bridging methylene group between a pair of pyrroles. Also, the pyrrole rings in corrin have fully saturated edge-carbons, that is, two hydrogens attached compared to only one in porphyrins.

Corrin's name reflects that it is the "core" of vitamin B12 (cobalamins), coordinating cobalt much as porphyrin binds to iron in heme. It has many derivatives called corrinoids, also known as cobalamines, corphyrins, corrins, or vitamin B12 compounds. Corrinoids have properties related to porphyrins, but:

• They are more flexible than porphyrins.
• They are not as flat as porphyrins.
• Because of the loss of the bridging methylene, and partly saturated pyrroles, they do not have a full conjugated character around the entire ring. Instead, the ring has a kind of "3/4" conjugation.

The related corroles (octadehydrocorrins) are fully aromatic.