A Matrix-Isolation and Quantum-Chemical Investigation of FeF4

摘要

Iron is the second most abundant metal in the earth's crust, and owing to this high natural abundance it can be considered as one of the most important elements. Chemically it plays an important role in the active sites of many enzymes and it is therefore given increasing attention as a cheap, non-toxic, and environmentally friendly alternative in organic catalysis.In both enzymatic and artificial catalytic reactions, oxidation and reduction processes are crucial. The most abundant oxidation states of iron are + 2 and + 3, but higher oxidation numbers up to + 6 are experimentally known. These higher oxidation states of iron are usually stabilized by oxygen, for example in the tetraoxoferrate(VI) anion [FeO4]~(2-), of which several salts are known. Beyond these anionic complexes, neutral iron oxides, such as [O2Fe(η~2-O2)], have been stabilized under cryogenic conditions in rare gas matrices. Furthermore, iron nitrido complexes in the +5 and +6 oxidation states have been successfully prepared in solution at low temperatures, as shown by Mossbauer and X-ray absorption spectroscopy.