Dolphin, D.H., Johnson, A.W., and Shaw, N. “Sulphitocobalamin”, Nature, 1963, 199, 170-171.

A wide range of cobalamins exist where the cyano group of the original vitamin B12 is replaced, for example, by water (vitamin B12), halides, nitrite, sulphur-containing groups, and alkyl groups (the coenzymes and analogues) and the nature of the ligand attached to the cobalt has a profound influence on the chemical and physical properties of the cobalamin.

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MeCo(III) and EtCo(III) etioporphyrin I derivatives were prepared by the treatment of the Co(py)Br complex with RMgX in (MeO)2C2H4 (R is alkyl). Spectral evidence was obtained for the Co(III) analogs with allyl, C6H11, and Ph groups. The N.M.R. spectrum of the Me compound indicates that the Co is bonded to Me and to the porphyrin ring, but not to C5H5N. The alkyl compounds are stable toward KCN except in light.