Mossbauer spectroscop

Mossbauer spectroscopic titration of [Me2Sn(IV)] and [MesSnflV)] hydroxides with ligands mimicking nucleic acid phosphate sites and with native DNA was the aim of work by Barbieri et al. A series of aqueous solutions of each system, formed by the organotin(IV) hydroxides and the phosphate ligands used... 

On the other hand, the [Bu2Sn(lV)] complexes of the O analogs of the above-mentioned ligands are linear oligomers. The FT-IR and Raman spectroscopic data indicated the presence of bidentate and/or monodentate -COO groups, nonlinear C-Sn-C bonds, and Sn-O bonds within the complexes. The results of Mossbauer spectroscopic measurements showed a Tbp arrangement around the central Sn atom in addition to the and structures. ... 

Caldeira J, R Eeicht, H White, M Teixeira, JJG Mourat, H Simon, 1 Moura (1996) EPR and Mossbauer spectroscopic studies on enoate reductase. J Biol Chem 271 18743-18748. 

The results of the XRD measurement showed that the Fe jAl, jPO catalyst was almost in amorphous state. Only a very broad peak at 29 of ca. 23 degree was observed. The Mossbauer spectroscopic study on this catalyst showed one doublet of iron with the isomeric shift of 0.31 mm s (a-Fe was used as the reference) and the quadrupole splitting of 0.62 mm s. These parameters are very close to those observed for FePO [13, 14], suggesting that the iron cation in the catalyst is tetrahedrally coordinated with oxygen and isolated by four PO tetrahedral units. Such coordination circumstance was suggested to be a key factor for the iron site effective for the oxidation of CH to CHjOH by H -Oj gas mixture [15]. 

After the reaction for 5 h in a reactant stream of CH , O, and Hj (P(CHJ= 33.7, P(0,)= 8.4 and P(H2)= 50.7 kPa), the catalyst was analyzed by XRD, Mossbauer and XPS studies. As regarding the XRD and Mossbauer spectroscopic measurements, obvious changes were not observed before and after the reaction. On the other hand, a marked change was observed in the XPS spectrum of the catalyst after the reaction. As shown in Fig. 2, besides the peak at 57.7 eV, which was the only peak of Fe3p obtained for the sample before the reaction and was ascribed to Fe(III), a clear shoulder at 56.1 eV was observed after the reaction. This can be ascribed to the Fe(ll) on the catalyst surface. The same phenomenon has been reported for FeP04 catalyst [13]. Such observations suggest the occurrence of the redox of iron between Fe(Iil) and Fe(II) during the reaction. We believe that this redox plays a key role in the formation of a new active center and thus is important in the selective oxidation of CH4... 

Russo, U., Long, G.J. Mossbauer spectroscopic studies of the high oxidation states of iron. In Long, G.J., Grandjean, F. (eds.) Mossbauer Spectroscopy Applied to Inorganic Chemistry, pp. 289-329. Plenum, New York (1989)... 

Fig. 2. Possible structures for a diiron(III) peroxide unit in the peroxo intermediate consistent with available Raman and Mossbauer spectroscopic data. The symbols N and 0 designate nitrogen and oxygen donor atoms of histidine and glutamate residues, respectively. Some of the latter must be bidentate to fill the coordination spheres.

TABLE 2. Structural determination of stannaalkanes, stannacycloalkanes and their derivatives by NMR and Mossbauer spectroscopic methods... 

Giitlich (1979) Mossbauer spectroscopic studies of spin crossover compounds [212]. 

Spectroscopic techniques may provide the least ambiguous methods for verification of actual sorption mechanisms. Zeltner et al. (Chapter 8) have applied FTIR (Fourier Transform Infrared) spectroscopy and microcalorimetric titrations in a study of the adsorption of salicylic acid by goethite these techniques provide new information on the structure of organic acid complexes formed at the goethite-water interface. Ambe et al. (Chapter 19) present the results of an emission Mossbauer spectroscopic study of sorbed Co(II) and Sb(V). Although Mossbauer spectroscopy can only be used for a few chemical elements, the technique provides detailed information about the molecular bonding of sorbed species and may be used to differentiate between adsorption and surface precipitation. 

In situ emission Mossbauer spectroscopic measurement of the hyper-fine magnetic fields on trivalent Fe-57 and tetravalent Sn-119 arising from divalent Co-57 and pentavalent Sb—119, respectively, yields valuable information on the chemical structure of adsorbed metal ions at the interface between hematite and an aqueous solution. 

Cardile, C.M (1988) Tetrahedral Fe in ferrihy-drite Fe Mossbauer spectroscopic evidence. Clays Clay Min. 36 537-539 Carlson, L. Schwertmann, U. (1980) Natural occurrence of feroxyhite (5 -FeOOH). Clays Clay Min. 28 272-280... 

Music, S. Vertes, A. Simmons, G.W Czako-Nagy, I. Leidheiser, H.Jr. (1982) Mossbauer spectroscopic study of the formation of Fe(III) oxyhydroxides and oxides by hydrolysis of aqueous Fe(III) salt solutions. J. Colloid Interface Sd. 85 256—266... 

St. Pierre,T.G. Bell, S.H. Dickson, D.P.E. Mann, S. Webb, J. Moore, G.R. Williams, R.J.P. (1986) Mossbauer spectroscopic studies of the cores of human, limpet and bacterial ferritins. Biochim. Biophys. Acta 870 127-134... 

Mossbauer spectroscopic study of reactions within rust layers. Corrosion Sd. 29 1329—... 

FABMS, 39 340-342 isolobal analogies, 39 378-381 ligand addition, elimination, and substitution reactions, 39 337-338 Mossbauer spectroscopic studies, 39 342-344... 

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