Iron atoms reacting with chemistry

Figures 4 and 5 Illustrate the chemistry of iron and scandium atoms reacting with water. As noted earlier, both Fe and Fe2 water adducts are formed and labeled "a" and "b", respectively, in Figure A. It is interesting that Fe2...0H2 can be photolyzed without photolyzing the Fe...OH2 adduct. The "d" peaks which result from photolysis of Fe2...0H2 indicate that a species with terminally bonded H and OH groups is formed. The photolysis of Fe2...0H2 would appear to lead to formation of the HFeFeOH species.

Rust is iron that has been oxidized. The oxidation of iron, or any iron alloy (See History of Chemistry ), can occur whenever iron is in the presence of oxygen and water. The chemical reaction involves electrons from the iron being transferred to oxygen atoms, which react with water molecules to eventually form iron oxides. The presence of ions, like salt or H3O+ in acidic solutions, can accelerate the rate of these reactions. Preventing rust usually requires a protective coating that prevents the iron from reacting with oxygen and water. 

Coordination modifies the chemical and physical properties of both the central atom and the ligands. Consider the chemistry of aqueous cyanide (CN ) and iron(II) (Fe " ) ions. The CN ion reacts immediately with acid to generate gaseous HCN, a deadly poison, and Fe ", when mixed with aqueous base, instantly precipitates a gelatinous hydroxide. The reaction between Fe " and CN produces the complex ion [Fe(CN)g] (d q), which undergoes neither of the two reactions just described nor any others considered characteristic of CN or Fe. Ions or molecules may be present in multiple forms in the same compound. The two Cl ions in [PtlNHjjjClJCl are chemically different, because one is coordinated and the other is not. Treatment of an aqueous solution of this substance with Ag" immediately precipitates the uncoordinated Cl as AgCl(s), but not the coordinated Cl just as it did for Werner s complexes discussed earlier. 

TT-cation radical complexes.In the reactions, oxoiron(IV) porphyrin rr-cation radicals of electron-rich porphyrins reacted fast with ROOH (i.e., catalase and peroxidase type of chemistry one-electron oxidation of ROOH) (Scheme 2, pathway A). On the other hand, oxoiron(IV) porphyrin rr-cation radicals of electron-deficient porphyrins reacted fast with olefins to yield epoxide products (i.e., cytochrome P450 type of chemistry oxygen atom transfer) (Scheme 2, pathway B). These results demonstrated that electron-deficient iron porphyrin complexes are better catalysts in hydrocarbon oxygenations by hydroperoxides, since these complexes can avoid the facile decomposition of oxoiron intermediates by ROOH (Scheme 2, pathway A). Indeed, highly electron-deficient iron(III) porphyrin complexes efficiently catalyze alkane hydroxylations by H2O2 in aprotic solvents. 

---