THE JOINT GAS ELECTRON-DIFFRACTION AND MASS-SPECTROMETRIC STUDY OF GEI4(G)+GE(S) SYSTEM - MOLECULAR-STRUCTURE OF GERMANIUM DIIODIDE

A mass spectrometric study was made of the GeI4(g) + Ge(s) system at 400-780 K. The conditions at which GeI2 is the main molecular species were determined. The electron diffraction patterns were recorded at 653 K with simultaneous mass spectrometric control of the vapour composition. The experimental molecular scattering intensity function was represented using the bond distances, force constants, and the concentrations of the molecular species present in the vapour. It was established that GeI2 has a non-linear geometry with r(alpha)(Ge-I) = 254.0(5) pm and a valence angle of 102.1(1.0)degrees. The correlations between the mean bond energies, the bond distances and the valence force constants of the germanium dihalides and tetrahalides are discused.