In situ coordination of Fe2+ to aromatic diamines intercalated into gamma-zirconium and gamma-titanium phosphates: Evidence from Mossbauer spectroscopy and thermal studies

Iron(II) can be exchanged into layered gamma-Zr(H(2)PO(4))(PO(4))-diamine and gamma-Ti(H(2)PO(4))(PO(4))-diamine composites (diamine = 2,2'-bipyridyl,1,10-phenanthroline,2,9-dimethyl-1,10-phenanthroline). Mossbauer spectroscopy indicates that an in situ iron-amine coordination occurs in the case of iron-bipyridyl- and iron-phenanthroline-gamma-zirconium phosphate: Fe(2+) low-spin trischelates [Fe(bipy)(3)](2+) and [Fe(phen)(3)](2+) are formed between the layers of the host; high-spin Fe(2+) also forms complexes in the interlayer region and the chromophores could be any of the possibilities provided by the formulation [FeN(x)O(6-x)] (x = 1-4). Iron(II) partially transforms into iron(III) when the former is not stabilized by the formation of strong complex species. The thermal behaviour of the exchanged compounds has been investigated and correlated with the composition of the materials. X-Ray patterns of some of the new materials are also reported.