DFT Calculations of the Electric Field Gradient at the Tin Nucleus as a Support of Structural Interpretation by ¹¹⁹Sn Mössbauer Spectroscopy

Abstract

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 corresponding calculated V values, produced a slope that is equal to 0.93 +/- 0.03 and a correlation coefficient R = 0.982. The value of Q obtained, 15.2 +/- 4.4 fm(2), is in agreement with that previously experimentally determined or calculated by analogous procedures. The calculation method is able to establish the sign of the electric field gradient component V(zz), in agreement with the sign of DeltaE determined experimentally by Mössbauer-Zeeman spectroscopy. The calculated structural parameters are in good agreement with the corresponding experimental data, determined by X-ray crystallography in the solid state, with average structural deviations of about 3 % for bond lengths and angles in the tin environment. Calculated values of DeltaE were obtained from the calibration fitting constant and from the values of V. By comparing experimental and calculated DeltaE parameters, the structure assignment of configurational isomers was successful in two test cases, in agreement with the experimental X-ray crystallographic structures. These results indicate that the method can be used as a tool to support the routine structure interpretation of tin compounds by (119)Sn Mössbauer spectroscopy.

Speciation and structure of tin(ii) in hyper-alkaline aqueous solution

“…The X-ray absorption spectra for tin were collected at the bending magnet beam-line Samba at the Soleil synchrotron facility, Paris, France, which operated at 2.75 GeV and a maximum current of 50 400 mA. The Samba beam-line covers the energy range 4-42 keV.…”

“…This Fourier transform has only a single peak related to the primary Sn-O bond distance at ~2.1 Å (~1.6 Å, not phase corrected). According to this single peak, tin(II) is expected to have a simple local environment, and no multiple 50 scattering from the atoms in the first coordination sphere was detected. This indicates low symmetry around tin(II).…”

“…In spite of these hurdles, the number of publications dealing with this particular aspect of solution chemistry steadily increases. For obvious reasons, metal ions with reasonable solubility (e.g., amphoteric ones) are most 50 intensely studied (e.g., Al(III) [7][8][9] , Ga(III) 10,11 , Cr(III) 12, 13 , Pb(II) 14 , Tl(I) 15,16 , etc.). Beside these, data for metal ions that are hardly soluble in alkaline conditions also emerge (e.g., Cu(II) 17 , Fe(III) 18 , actinides 19 , etc.)…”

“…Figure 6). On the calculated spectra of both species, peaks are seen at around 430 and 490 cm −1 , with 50 larger intensity corresponding to the band at the smaller wavenumber. The same can be observed on the experimental spectrum.…”

Synthesis, characterization, and in vitro antimicrobial activity of organotin(IV) complexes with triazolo-pyrimidine ligands containing exocyclic oxygen atoms

“…All calculations were performed by the Gaussian98 program package [13]. The 119 Sn Mö ssbauer nuclear quadrupole splitting was calculated by the calibration formula DE calcd = 0.93 AE V ± 0.58 mm s À1 [14], where…”