Structure of monomeric and dimeric molecules of erbium tribromide from gas-phase electron diffraction data

摘要

The structural investigation of molecules in the vapour over erbium tirbromide has been performed by synchronous gas-phase electron diffraction and mass spectrometry at T = 1095(10)K. The presence of a small amount (2.5%) of dimeric molecules was detected. For ErBr_3 the thermal average bond length r_g(Er-Br) = 258.2(6) pm and the valence angle angle_g(Br-Er-Br) = 116.0(14) deg have been determined. This valueof the average bond angle corresponds to the palnar or near planar equilibrium structure of the monomic molecule taking into account the shrinkage effect. The structural parameters of Er_2Br_6 have also been obtained.