The coordination of sterically hindered bases to metalloporphyrins

✍ Scribed by Robert G. Little; Brian M. Hoffman; James A. Ibers

• Book ID: 104105877
• Publisher: Elsevier Science
• Year: 1974
• Weight: 588 KB
• Volume: 3
• Category: Article
• ISSN: 0006-3061
• DOI: 10.1016/s0006-3061(00)80070-8

✦ Synopsis

AE3STRACT

The coordination of stericzdly hindered nitmgenous bases tn octaethylporphiitocobalt(II), (Ca(OEI?)), has been studied by epr techniques. It is shown that, despite reports in the literature to the contrnry, 2,4,6-t& methylpyridiie (s-collidiie) and 2,6&methylpyridine (2,fSlutidine) do not coordinate to cobalt porphyrins_ On the basis of progressive purification of the s-collidine it is shown that previous reports of its coordination result from the presence of impurities in the material. We have also found that Zmethylpyridine (2picoline) at best coordinates weakly. Thii work, along with the results of independent structural studies, shows that the trigger mechanism for the allosteric lie of hemoglobin cannot apply unmodified to cobal&aubatituted hemoglobin.