Mononitrosyl–iron compounds (MNICs) of the Enemark–Feltham FeNO}7 type can be divided into a doublet (S=1/2) and a quartet (S=3/2) spin variant. The latter relies on weak‐field co‐ligands such as amine carboxylates. Aqua‐only co‐ligation appears to exist in the long‐known “brown‐ring” [Fe(H2O)5(NO)]2+ cation, which was prepared originally from ferrous salts and NO in sulfuric acid. A chloride variant