ELECTRON-DIFFRACTION STUDY OF THE STRUCTURE THE NBBR4 MOLECULE

The structure of the NbBr4 molecule is studied in synchronous electron diffraction and mass spectrometry experiments. Gaseous niobium tetrab romide is synthesized in the course of the experiment during the inter action of niobium chips with bromine at 496 degrees C. Analysis of the geometrical models of the NbBr4 molecules of C-2v, C-3v, D-2d, and T- d symmetries shows that the tetrahedral model is preferable. The therm ally averaged parameters of the effective configuration of the NbBr4 m olecule are as follows: r(g)(Nb-Br)=2.418(5) Angstrom, l(Nb-Br)=0.074( 2) Angstrom r(g)(Br-Br)=3.921(16) Angstrom, l(Br-Br)=0.271(12) Angstro m, delta(Br-Br)=0.027(18) Angstrom.