SIMULTANEOUS ELECTRON-DIFFRACTION AND MASS-SPECTROMETRIC STUDY OF THESTRUCTURE OF THE MOF5 MOLECULE

Electron diffraction data for the MoF5 molecule are analyzed in terms of an r(alpha) structure. Three models of the geometrical structure, w hich have D-3h, C-4v, and C-2v symmetry, are considered It is confirme d that a distorted bipyramid of C-2v symmetry is the best model that i s in agreement with experimental electron diffraction data. The model has three different types of nuclear Mo-F distances: r(alpha)(Mo-F-1eq ) = 1.720(5) Angstrom, r(alpha)(Mo-F-2eq) = 1.826(7) Angstrom, r(alpha )(Mo-F-ax) = 1.825(7) Angstrom. The bond angle between the pseudoaxial bonds is 168.1(06)degrees, and the angle between the Mo-F-2eq pseudoe quatorial bonds is 122.6(0.8)degrees. The r(alpha)(Mo-F-1eq) and r(alp ha)(Mo-F-2eq) distances differ significantly. Possible reasons for thi s are discussed.