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7956640 
Journal Article 
CRYSTAL AND MOLECULAR-STRUCTURE OF CYCLOTRIBORAZANE, INORGANIC ANALOG OF CYCLOHEXANE 
Corfield, PW; Shore, SG 
1973 
Yes 
Journal of the American Chemical Society
ISSN: 0002-7863
EISSN: 1520-5126 
95 
5 
1480-1487 
English 
WOS:A1973P014300022 
The crystal structure of cyclotriborazane, (BH2NH2)3, has been determined at room temperature from X-ray diffraction data. The compound crystallizes in the orthorhombic space group Pbcm, with a = 4.403 (3), b = 12.210 (7), and c = 11.227 (10) Å. A set of 450 reflections was obtained by counter methods. The molecule has the chair form, with molecular symmetry very close to C3ν, one of the mirror planes being required by the space group, and the threefold axis lying along a. Conventional, full-matrix least-squares refinement of 59 variables converged with the weighted R factor 0.049. On including four extra variables describing the charge distribution in the molecule, this R factor fell to 0.035. The average partial charges found on each type of atom are as follows: B, +0.7 e; N, —0.3 e; H(B), —0.3 e; and H(N), +0.1 e. The relatively large charges on the hydrogen atoms are consistent with the high heat of sublimation. The calculated dipole moment based upon these point charges at the atomic positions is 3.0 D, which compares well with the experimental value. The ring atoms oscillate as a rigid group, and the corrected B-N bond distance is 1.576 (2) Å. The equatorial B-H distances average 1.11 (1) A and appear to be longer than the axial B-H distances, which average 1.08 (1) Å. 1973, American Chemical Society. All rights reserved.