Search results for "Quadrupole splitting"
showing 10 items of 50 documents
INTERACTIONS OF ORGANOTIN(IV) HALIDES WITH REDUCED GLUTATHIONE IN AQUEOUS-SOLUTION
1993
Abstract Glutathione (GSH) is a compound extremely common among many living organisms in which it plays a fundamental role in the processes of detoxification. Also, organotin(IV) derivatives are more and more commonly used in technological processes or as antitumor drugs. So it seemed interesting to investigate the possible interactions between GSH and organotin compounds in water. Particularly, it has been studied because of its role in the organic radicals linked to the tin center on the stoichiometry and the structure of the adducts. Information was obtained following the reaction between Me n SnCl 4-n (n = 1 to 3) and GSH by Mossbauer and NMR spectroscopies on the assumption that change…
The interaction of organotins with native DNA
1992
The compounds R2SnCl2 and R3SnCl (RMe, Et, nBu, nOct, Ph, in ethanol solution) as well as the aqueous species [Me2Sn(OH2)n]2+ and [Me3Sn(OH2)2]+, react with aqueous native DNA, yielding solid phases. According to the pointcharge model treatment of the 119Sn Mossbauer parameter nuclear quadrupole splitting, trans-octahedral R2Sn(O2PXY)2, and trigonalbipyramidal R3Sn(O2PXY), (RMe, Et, nBu), would occur in the pellets, the tin atoms being coordinated by phosphodiester groups of the nucleic acid. The precipitates from Ph2SnIV would consist of the DNA complex as well as of the Ph2SnIV distannoxane obtained by hydrolysis of the reactant, whilst nOct2SnCl2, nOct3SnCl and Ph3SnCl would mainly yield…
Preparation and structural studies on dibutyltin(IV) complexes with pyridine mono- and dicarboxylic acids
2004
Abstract A number of organotin(IV) complexes with pyridine mono- and dicarboxylic acids (containing ligating –COOH group(s) and aromatic {N} atoms) were prepared in the solid state. The bonding sites of the ligands were determined by means of FT-IR spectroscopic measurements. It was found that in most cases the –COO− groups form bridges between two central {Sn} atoms, thereby leading to polymeric (oligomeric) complexes. On this basis, the experimental 119Sn Mossbauer spectroscopic data were treated with partial quadrupole splitting approximations. The calculations predicted the existence of complexes with octahedral (oh) and trigonal-bipyramidal (tbp) structures, but the formation of comple…
Mössbauer spectroscopic studies on compounds containing tin-cadmium and tin-zinc bonds
1975
The Mossbauer parameters of compounds Ph3Sn MCl · TMED (M = Cd, Zn; TMED = N,N,N′,N′-tetramethylethylenediamine), (Ph3Sn)2CdL2 (L2 = TMED, 2,2′-bipyridine and o-phenanthroline) and (Ph3Sn)2 Zn · TMED have been determined and are discussed in connection with Mossbauer data concerning Ph3SnIV derivatives with other Sn-metal bonds. The isomer shift values suggest a high s character in SnCd and SnZn bonds resulting in deviations from regular tetrahedral environments around tin. Experimental quadrupole splittings and calculated partial quadrupole splitting values indicate reduced donor abilities towards the tin atom of an individual Ph3SnIV moiety by Cd-and Zn(Ph3Sn)1−nClnL2 (i.e., the remaini…
DFT Calculations of the Electric Field Gradient at the Tin Nucleus as a Support of Structural Interpretation by119Sn Mössbauer Spectroscopy
2005
DFT calculations, using an all-electron basis set and with full geometry optimization, were performed on 34 Sn(II) and Sn(IV) compounds of known structure and (119)Sn Mössbauer parameters, to obtain the theoretical values of the electric field gradient components, V(xx), V(yy), and V(zz), at the tin nucleus. These were used to determine the quantity V = V(zz)[1+ 1/3((V(xx) - V(yy))/((V(zz))(2)](1/2), for each investigated compound, which is related to the quadrupole splitting (DeltaE) parameter according to DeltaE = 1/2eQV, where e is the electronic charge and Q is the quadrupole moment of the tin nucleus. The linear fitting of the correlation plot of the experimental DeltaE, versus the cor…
The prediction of the nuclear quadrupole splitting of 119Sn Mössbauer spectroscopy data by scalar relativistic DFT calculations.
2006
The electric field gradient components for the tin nucleus of 34 tin compounds of experimentally known structures and Sn-119 Mossbauer spectroscopy parameters were computed at the scalar relativistic density functional theory level of approximation. The theoretical values of the electric field gradient components were used to determine a quantity, V, which is proportional to the nuclear quadrupole splitting parameter (Delta E). In a subsequent linear regression analysis the effective nuclear quadrupole moment, Q, was evaluated. The value of (11.9 +/- 0.1) fm(2) is a significant improvement over the non-relativistic result of (15.2 +/- 4.4) fm(2) and is in agreement with the experimental val…
Crystal structure and mössbauer spectroscopy studies of the ferrimagnetic complex bimetallic salt hexaamminechromium (III) hexachloroferrate (III), […
1992
The crystal and molecular structures of the ferrimagnetic bimetallic complex salt hexaamminechromium(III) hexachloroferrate(III), [Cr(NH3)6][FeCl6], have been determined from single-crystal, three-dimensional x-ray diffraction counter data. The compound crystallizes as orange coloured crystals in the space groupC2/c of the monoclinic system with Z=4 and has cell dimensionsa=11.325(1) A,b=11.387(1) A,c=11.233(1) A, and β=90.83(1)A. The structure was refined by using segmented block diagonal least-squares techniques to discrepancy indices R and Rw of 0.0233 and 0.0285, respectively. The metal ions occupy sites with symmetry $$\bar 1$$ and are nearly octahedrally coordinated. In the [FeCl6]3− …
Mössbauer spectroscopic studies of clusters Mn2(CO)8[μ-Sn(hal)Mn(CO)5]2 (hal = Cl, Br) and related Mn and Re compounds
1977
Abstract In order to be acquainted with the nature of bonds at Sn involved in the title compounds, as well as to get information on the configuration of the strictly related derivatives I2Sn2Mn4(CO)18 and Cl2Sn2Re4(CO)18, the Mossbauer spectroscopic investigation reported in this paper has been carried out. The experimental parameters (isomer shifts, δ; nuclear quadrupole splittings, ΔE; for the bromide derivative only, the asymmetry parameter η and the sign of the nuclear quadrupole coupling constant e2qQ) have been discussed in connection with data concerning compounds with tin-transition metal bonds, mainly hal2Sn[Mn(CO)5]2 (hal = Cl, Br) and ClSn[Mn(CO)5]3. Rationalizations of ΔE and η …
Interpretation of Mössbauer Parameters of Iron Compounds
1978
The task of this section is to show that for the interpretation of Mossbauer parameters — in the present case of electron densities, field gradients and magnetic hyperfine fields — bonding effects can play an important role, and free-ion or crystal field approaches may be a poor approximation.
Homoleptic iron(II) complexes with the ionogenic ligand 6,6′-Bis(1H-tetrazol-5-yl)-2,2′-bipyridine: spin crossover behavior in a singular 2D spin cro…
2015
Deprotonation of the ionogenic tetradentate ligand 6,6′-bis(1H-tetrazol-5-yl)-2,2′-bipyridine [H2bipy(ttr)2] in the presence of FeII in solution has afforded an anionic mononuclear complex and a neutral two-dimensional coordination polymer formulated as, respectively, NEt3H{Fe[bipy(ttr)2][Hbipy(ttr)2]}·3MeOH (1) and {Fe[bipy(ttr)2]}n (2). The anions [Hbipy(ttr)2]− and [bipy(ttr)2]2– embrace the FeII centers defining discrete molecular units 1 with the FeII ion lying in a distorted bisdisphenoid dodecahedron, a rare example of octacoordination in the coordination environment of this cation. The magnetic behavior of 1 shows that the FeII is high-spin, and its Mössbauer spectrum is characteriz…