"Cyanocobalamin may also be used to prepare precursors of the cyanometal-centered ring hereinabove described, in which M is other than cobalt, by reacting a solution of cyanocobalamin with a chelating ligand which has a stronger affinity for cobalt than the cyanocobalamin residue, such as EDTA, preferably to form an insoluble cobalt-chelating ligand complex which may easily be separated." . . . .