Structural features of potassium and cesium dodecahydro-closo-dodecaborates(2-) according to1H and11B NMR data
Tóm tắt
The structural and dynamic characteristics of the salts K2B12H12 (I) and Cs2B12H12 (II), containing an icosahedral closo-anion B12H12
2-, were investigated by the NMR method. Disagreement was found between the obtained NMR data and the published results from an x-ray crystallographic analysis with respect to the position of the H and B atoms in the crystal lattices of the compounds. The1H and11B NMR data give reason to suppose that compounds (I) and (II) can be assigned to the quasiperiodic crystal class with respect to the positions of the H and B atoms. From analysis of the line shapes in the1H NMR spectra the interatomic separations r(B-H) in the B12H12
2− anion in the salts (I) and (II) were determined (1.21±0.01 Å). Activation dynamics characterized by activation barriers of 54.4 and 38.9 kJ/mole respectively were obtained for the B12H12
2− anions.
Tài liệu tham khảo
S. G. Kozlova, V. V. Volkov, S. G. Vasil'eva, et al., Metalloorgan. Khimiya,3, No. 4, 887–891 (1990).
A. Zalkin, T. E. Hopkins, and D. H. Templeton, Inorg. Chem.,6, No. 10, 1911–1915 (1967).
D. St. Clair, A. Zalkin, and D. H. Templeton, J. Am. Chem. Soc.,92, No. 5, 1173–1179 (1970).
A. M. Soldate, J. Am. Chem. Soc.,69, 987–988 (1947).
B. Aubrey and P. Altschuller, J. Am. Chem. Soc.,77, No. 21, 5455–5471 (1955).
A. Almenningen, G. Gunderson, and A. Haaland, Acta Chem. Scand.,22, 328–334 (1968).
P. H. Bird and M. K. Churchill, Chem. Commun., 403–405 (1967).
N. N. Greenwood, Comprehensive Inorganic Chemistry, Vol. 1, Pergamon, Oxford (1973), p. 763.
A. Tippe and W. C. Hamilton, Inorg. Chem.,8, 464–470 (1969).
W. H. Eberhard, B. Crawford, and W. N. Lipscomb, J. Chem. Phys.,22, 989–903 (1954).
J. A. Wunderlich and W. N. Lipscomb, J. Am. Chem. Soc.,82, 4427–4428 (1960).
N. N. Greenwood and J. H. Morris, Proc. Chem. Soc., 338–340 (1963).
V. V. Volkov and I. S. Posnaya, Zh. Neorgan. Khim.,24, No. 10, 2824–2826 (1976).
D. Uo and É. I. Fedin, Fiz. Tverd. Tela,4, No. 8, 2233–2237 (1962).
Yu. N. Sirotin and M. P. Shaskol'skaya, Principles of Crystal Physics [Russian translation], Mir, Moscow (1979).
L. Danser, XII European Crystallographic Meeting: Collected Abstracts, Moscow (1989), Vol. 1, p. 10.
A. Abraham, Nuclear Magnetism [Russian translation], IL, Moscow (1963).