• DOI:10.1007/BF00744504
• Corpus ID: 95512697

Electron-diffraction investigation of the molecular structure of potassium fluoroberyllate

@article{Spiridonov1972ElectrondiffractionIO,
  title={Electron-diffraction investigation of the molecular structure of potassium fluoroberyllate},
  author={Victor P. Spiridonov and E. V. Erokhin and Yu. A. Brezgin},
  journal={Journal of Structural Chemistry},
  year={1972},
  volume={13},
  pages={295-296},
  url={https://api.semanticscholar.org/CorpusID:95512697}
}

• V. P. Spiridonov, E. V. Erokhin, Yu. A. Brezgin
• Published 1 March 1972
• Chemistry
• Journal of Structural Chemistry

exist in the literature [2-6]. The existence of molecules of the composition MIBeF3 in the vapor phase is mentioned in all these works. Thus, a detailed mass-spectrometr ic investigation of the system NaF-BeF 2 [6] showed that there exists a molecule with the composition NaBeg a in the vapor at ll00~ along with other components of lesser percentage when the composition of the condensed phase is 30 mole % BeF 2. We attempted to investigate the vapors of this system by electron-diffrac tion at… 

exist in the literature [2-6]. The existence of molecules of the composition MIBeF3 in the vapor phase is mentioned in all these works. Thus, a detailed mass-spectrometr ic investigation of the system NaF-BeF 2 [6] showed that there exists a molecule with the composition NaBeg a in the vapor at ll00~ along with other components of lesser percentage when the composition of the condensed phase is 30 mole % BeF 2. We attempted to investigate the vapors of this system by electron-diffrac tion at 1300-1400~ corresponding to a condensed phase of this composition. It was found from an interpretation of the electron-diffrac tion patterns that the BeF 3 fragment has a right triangular structure with the Be atom in the center and with a value for r(Be-F) = 1.49 %. However, our attempt to ascertain the location of the Na atom in the molecule from the electron-diffrac tion patterns we obtained were not successful, which is possibly explained by the presence of other components with considerable dispersibility under the conditions of the electron-diffrac tion experiment. In order to ascertain the location of the alkali metal atom in a molecule of the type MIBeFa, we investigated the structure ofKBeF 3 in this work. By analogy with the NaF-BeF2 system, a composition of the condensed phase for the KF-BeF2 system containing 33 mole % of BeF2 was used to carry out the experiments. Preliminary experiments had shown that the electxon-diffrac tion patterns of the vapors obtained for the composition of the solid phase taken above differ from the electron-diffrac tion patterffs of the starting components of the system and could not be interpreted as the electron-diffrac tion patterns of a simple mixture of KF and BeF z vapors, The work was carried out on an electron-diffrac tion camera designed for investigating difficult-to-vol atilize compounds using the secmr-microphoto metrie method of exposing and treating the electron-diffrac tion patterns. A fusion of the substances was volatilized from a nickel ampule at 1000-1100~ the outflow of the vapor was in the direction of the electron beam. After each exposure, the ampule was carefully fired until the remainder of the salts was completely eliminated, and it was again charged with the initial fusion. The exposures were carried out atvoltages of 40 and 60 kV at a nozzle-to-plate distance of about 515 ram. Elimination of the molecular component of the scattering intensity sM(s) was carried out using a B~SM-4 computer according to a special program [7] while accounting for any correction in the sector function. An analysis of the experimental data obtained was carried out by the least squares method with successive refinement of the parameters as applied to the sM(s) curve. The initial approximation for the parameters was obtained from the radial distribution curve. The initial values of the parameters were refined on the basis of three variants of a model of the KBeF 3 molecule, namely those based on the triangular BeF 3 fragment with the K atom arranged as foIIows: