Simultaneous electron diffraction and mass-spectrometric study of the structure of the MoF5 molecule

Electron diffraction data for the MoF₅ molecule are analyzed in terms of an r_a structure. Three models of the geometrical structure, which have D_3h, C_4v, and C_2v symmetry, are considered. It is confirmed that a distorted bipyramid of C_2v symmetry is the best model that is in agreement with experimental electron diffraction data. The model has three different types of nuclear Mo-F distances: r_α(Mo-F_1eq) = 1.720(5) Å, r_α(Mo-F_2eq) = 1.826(7) Å, r_α(Mo-F_ax) = 1.825(7) Å. The bond angle between the pseudoaxial bonds is 168.1(0.6)?, and the angle between the Mo-F_2eq pseudoequatorial bonds is 122.6(0.8)?. The r_a(Mo-F_leq) and r_a(Mo-F_2eq) distances differ significantly. Possible reasons for this are discussed.