Keywords: Corrin-IUPAC.svg de Struktur von Corrin;<br />en Structure of corrin I've added ring numbering to the structure according to 1975 IUPAC standard See http //www chem qmul ac uk/iupac/misc/B12 html r1 Note that there is no position 20 - to match porphyrins positions 20-23 from very early literature were incremented to 21-24 See for example Dorothy Crowfoot Hodgkin Proceedings of the Royal Society of London Series A Mathematical and Physical Sciences Vol 288 No 1414 Nov 16 1965 pp 294-305 http //www jstor org/pss/2415001 Corrin svg 2009-11-10 02 24 UTC Corrin svg NEUROtiker derivative work Mike Serfas <span class signature-talk >talk</span> subst LOCALMONTHABBREV subst LOCALYEAR ~~~ Own work al</nowiki> Uploaded with derivativeFX Tetrapyrroles |