Molecular structure of BiBr3: An electron diffraction study

The molecular structure of BiBr3 was determined by gas-phase electron diffr action. The principal geometrical parameters are r(alpha)(Bi-Br)= 2.567 +/- 0.005 Angstrom and angle(alpha)Br-Bi-Br = 98.6 +/- 0.2 degrees. The force field of the molecule was obtained by a normal coordinate analysis utilizin g both experimental vibrational frequencies and electron diffraction mean a mplitudes of vibration, The variation of bond lengths and bond angles withi n the Group 15 trihalides is consistent with the expected trend, except tha t all bismuth trihalide bond angles appear to be somewhat large.