Vibrational Spectra of MoF6 and TcF6

Abstract

Infrared spectra of gaseous MoF₆ and TcF₆ from 6–43 μ, the Raman spectrum of MoF₆ gas, and an incomplete Raman spectrum of liquid TcF₆ are reported. These are interpreted in terms of the octahedral point group 0_h. The fundamental frequencies for MoF₆ are 741(ν₁), 643(ν₂), 741(ν₃), 264(ν₄), 306(ν₅), and 190(ν₆). For TcF₆ they are 705(ν₁), 551(ν₂), 748(ν₃), 265(ν₄), 255(ν₅) and ν₆ has not been determined. Differences between the spectra of MoF₆ and TcF₆ are explained as a consequence of orbital degeneracy in the ground state of the latter, in analogy with similar differences in the 5d series.