“Increased‐valence” formulas for the iron–ligand bonding of some ferrohaemoglobin compounds

Valence formulas are constructed for the iron–ligand groups of the oxy‐, carboxy‐, nitric oxide‐, and nitrosobenzene derivatives of haemoglobin. To do this, the newly developed “increased‐valence” theory3 is used. The most stable of these valence formulae are able to account simply for certain iron‐ligand properties, with the iron remaining essentially as ferrous, as it is in haemoglobin.