Molecular Structure of BiBr3: An Electron Diffraction Study

The molecular structure of BiBr3 was determined by gas-phase electron diffraction. The principal geometrical parameters are r∝(Bi—Br) = 2.567 ± 0.005 A and ∠221D;Br—Bi—Br = 98.6 ± 0.2°. The force field of the molecule was obtained by a normal coordinate analysis utilizing both experimental vibrational frequencies and electron diffraction mean amplitudes of vibration. The variation of bond lengths and bond angles within the Group 15 trihalides is consistent with the expected trend, except that all bismuth trihalide bond angles appear to be somewhat large.