Mössbauer Spectra of Some Iron Complexes

Abstract

Mössbauer spectra were obtained for the following coordination compounds: iron phthalocyanine, ferrocene, iron carbonyl, iron III acetylacetonate, and iron II acetylacetonate dipyridine; for the following complex ion salts iron II trisphenanthroline chloride, iron III EDTA (monosodium salt), iron II EDTA, hemin, ferricium picrate, sodium nitroprusside, and some ferro- and ferricyanides. The isomer shift (relative to stainless steel) for iron II has the value expected for an inorganic ion only for iron II EDTA. In the other complexes the shifts are about 0.4 mm/sec, except ferrocyanide which is near zero. For iron III only hemin and ferricyanide have unusually small isomer shifts. The large negative isomer shift in sodium nitroprusside suggests iron IV. Except for ferrocyanide quadrupole splittings occurred in iron of valence 0, II, and IV and were observed for both spin-paired and spin-unpaired complexes. Splittings varied widely, however not exceeding those for inorganic ferrous salts. Sodium ferricyanide showed an unexpected quadrupole splitting. Other iron III complexes gave broad and unsymmetrical spectra.

Acid–base behaviour of the ferricyanide ion in perchloric acid media. Spectrophotometric and kinetic study

“…The blue precipitate, once recovered, isolated, and dried, gave an IR spectrum coincident with that of a sample of Prussian Blue obtained by mixing ferrocyanide and ferric ions, and also with that of a sample of Turnbull Blue obtained by mixing ferricyanide and ferrous ions; it is well known that both species are the same, ferric ferrocyanide, since ferricyanide oxidizes ~e ' + to ~e~+ , being itself reduced to ferrocyanide (45)(46)(47)(48). There exist, in fact, two different types of Prussian Blue: (a) soluble Prussian Blue, Fe1'1M+Fe11(CN)6, which is formed when the alkaline ion M+ is in excess, and (b) insoluble Prussian Blue, Fe4[Fe(CN)6]3, when the alkaline and ferric ions are present in similar amounts (49, 50); the IR spectra of both species are identical.…”

Iron(III) Spin Crossover Compounds

“…The X-ray structure of [Fe(acetylacetonato) 3 ] has been known for almost 50 years and consists of an Fe(III) ion in a fairly regular octahedral environment of oxygen atoms with Fe-O=1.95 [88]. For the unsubstituted complex and for various complexes in which the ligand is substituted at the 2position (X=Cl, Br, I, CH 3 , C 6 H 5 , NO 2 ) 57 Fe Mössbauer spectra and the magnetism indicate that they are purely high spin [89][90][91][92]. However, for the complex derived from 4,4,4-trifluoro-1-(3-pyridyl)-1,3-butane-dione the temperature dependence of the magnetic moment (3.69 B.M.…”

Mössbauer Spectroscopy of Metal Sandwich Compounds*

“…The metallocarboranes have been discussed in recent review^,^^^^" and the synthesisJ7 and structure3* of a sulfur analogue have been reported. The Mossbauer spectral data for several of these compounds are given in TABLE 4 and FIGURES 2, 3 and 4. Note that the isomer shifts are reduced from the ferrocenevalue and that the residual quadrupole splittings for the iron(II1) systems are larger than the analogous t .…”