Darstellung, schwingungsspektren und Normalkoordinatenanalyse der Bromo-Iodo-Rhenate(IV), [ReRrnI6-n]2-, n = 0-6 / Preparation, vibrational spectra, and normal coordinate analysis of bromo-iodo-rhenates(iv), [ReRrnI6-n]2-, n = 0-6

Abstract

The IR and Raman spectra of the ten bromo-iodo-rhenates(IV) [ReBrnI6-n]2-, n = 0 -6 , including the geometrical isomers for n - 2,3,4, have been recorded at 80 K. The vibrational spectra are completely assigned according to point groups Oh, D4h, C4v, C3v, and C2v, as supported by normal coordinate analyses based on a general valence force field. Due to the different mms-influences Br < I in asymmetric axes Br•-Re-I', the Re-I' bonds are strengthened and the Re-Br• bonds are weakened, as indicated by valence force constants, for Re-I' on average 8,5% higher and for Os-Br• 8,3% lower, as compared with the values calculated for symmetric I-Re-I and Br-Re-Br axes, respectively