Sn Mossbauer Spectroscopy

The various, solid-state stereochemistries just described may often be distinguished fairly readily by Sn Mossbauer spectroscopy 5-9, 452), particularly from the value of the quadrupole splitting parameter, AEq (see Table II). 

For example, octahedral rans-R2SnX4 complexes give approximately twice the quadrupole splitting observed for the cis-octahedral analogs 7,8). More recently, temperature-dependent Mossbauer measurements have been used in conjunction with Raman spectroscopy to determine molecular weights 453) and lattice rigidity 460) of various organotin compounds. 

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DNA], with varying ligand organotin(IV) molar ratios, frozen at 77.3 K, were monitored by Sn Mossbauer spectroscopy. 

The structure and dynamics for some representatives of the series of [Me2Sn(IV)] , [MeSn(IV)] , and inorganic Sn(IV) complexes with (S, Nj-contain-ing donors have been determined by Sn Mossbauer spectroscopy and are reported in Ref. (292). 

Barbieri, R. Pellerito, L. Ruisi, G. Silvestri, A. Barbieri-Paulsen, A. Barone, G. Posante, S. Rossi, M. Sn Mossbauer spectroscopy studies on the interaction of organotin(IV) salts and complexes with biological systems and molecules. In Gianguzza, A. Pelizzetti, E. Sammartano, S. (Eds.), Chemical Processes in Marine Environments, Springer Verlag, Berlin, 2000 Chapter 12, p. 229. 

About 1000 papers are published annually on organotin chemistry, and we have been able to include only 5% of these. We have deliberately avoided treating in depth those aspects of the subject that have been thoroughly reviewed recently, and, in particular, we have avoided duplicating the excellent surveys of the use of organotin compounds in organic synthesis (4), of " "Sn Mossbauer spectroscopy (5-9), and of Sn NMR spectroscopy (10-12) that are available. 

Applications of " Sn Mossbauer Spectroscopy to the Study of Organotin Compounds, 9, 21... 

Shinjo et al. have investigated a number of multilayers and interfaces, also by Sn Mossbauer spectroscopy [437 39], as well as different kinds of multilayers of Au/TM with transition metals TM = Fe, Co, Ni [440 142]. 

In the following section, we describe the case of adsorption of a Sn complex onto a palladium oxide suspension. In an alkaline medium (a basic PdO hydrosol), chlorides in the SnCL complex are substituted in the coordination sphere of tin(IV) by hydroxo anions, which are in excess, yielding the stannate Sn(OH)g complex. The Sn Mossbauer spectroscopy spectrum of a bimetallic sol (frozen in liquid nitrogen) is compared with a true stannic solution. At the same tin concentration, it shows the changes in the Sn environment due to adsorption onto the PdO surface (Fig. 13.27). The isomer shift S is found to be close to zero for the stannate solution and increases when contacted with the PdO suspension, indicating a modification of the coordination sphere of tin. The increase in 5 can be correlated to an increase in the core level electronic density of tin. The quadrupole splitting A, is related to a modification of the symmetry of the close environment of tin, due to adsorption of Sn(OH)g complexes onto the PdO colloidal nanoparticles. 

FIGURE 13.35. Effect of reduction temperature on kinetic constants and % of alloyed phases determined by Sn Mossbauer spectroscopy. 

However, " Sn Mossbauer spectroscopy allows even much better characterization of Pt/Sn bimetallic nanoparticles. For example, with silica-deposited platinum-tin particles of homogeneous size (1.7 and 4.0nm, respectively, for two different samples) it has been demonstrated that (Figure 2.17) ... 

Anionic Rearrangement of Organosilicon and Germanium Compounds, 16, 1 Application of 13C-NMR Spectroscopy to Organo-Transition Metal Complexes, 19, 257 Applications of " "Sn Mossbauer Spectroscopy to the Study of Organotin Compounds, 9, 21... 

Based on the IR, Sn NMR and Sn Mossbauer spectroscopy, the tin atom in tetraorganotin derivative 363a is suggested to be tetracoordinate, but it is pentacoordinate both in the iodide 363b due to the O Sn interaction and in the dithiocarbamate 363c due to the bidentate mode of the thiocarbamate ligand . ... 

Mossbauer spectroscopy is the study of recoilless resonant fluorescence " Sn Mossbauer spectroscopy has been found to be a most usefifl method for studying the bonding and stereochemistry of tin compounds in the solid state. The two most important parameters are the isomer shift (5, mm s ) and the quadrupole sphtting (A q, nuns ), although the recoil-free fractions and temperature coefficients can also supply useful structural indications. 

Besides oxide supported Sn-Ru catalysts, carbon supported catalysts also find application in hydrogenation reactions. Sn Mossbauer spectroscopy was used to investigate the tin component of ruthenium and tin supported on activated carbon catalysts containing 2 wt. % ruthenium and having Sn/(Sn-f Ru) ratios between zero and 0.4. Four major components in the Sn Mossbauer spectra were attributed to both Sn(II) and Sn(IV) oxides and to Ru-SnOx species formed on the surface of ruthenium metal particles. In addition to this " Sn spectra reveal the presence of minor amounts of Ru3Sn7 alloy phase. ... 

Mossbauer spectroscopy has been applied " to dithiolenes in several instances. In the early phases of dithiolene chemistry, it allowed the assignment of a dimer structure to the Fe dithiolenes before crystallographic data were available.A more recent application of Mossbauer spectros-copy concerned monomeric and polymeric Fe dithiolenes. Through " Sn Mossbauer spectroscopy, a large number of formally four-, five- and six-coordinate Sn complexes with mnt lig-ands and with other sulfur ligands were investigated. 

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