The role of jahn-teller effect in formation of anticorrosive protective layers of nitrilo-tris-methylene-phosphonates on the steels surface

The substances forming anticorrosive protective layers of nitrilo-tris-methylene-phosphonates on a steel surface are isolated and investigated: nitrilo-tris-methylene-phosphonate coordination complexes of chrome(II) and iron(II). Their molecular and electronic structure and crystal packing are investigated. Unusual resistance of the Cr(II) complex to influence of air and the oxygen-saturated water is noted. It appeared that the Cr and Fe complexes are almost insoluble in water, unlike earlier studied isostructural compounds of zinc and copper. Their ability to form protective layers on a steel surface is explained by it. Difference of properties of the Cr and Fe complexes from properties isostructural it the Cu and Zn complexes is explained by various nature of Jahn-Teller distortion of coordination octahedrons of these metals.