The vibrational properties of some gold(iii)-halide complexes

Raman and i.r. spectra of a range of gold complexes of the form LAuX3 (L = C6H5)3P, (C2H5)3P, pyridine, lutidene and α-picoline; X = Cl− or Br−) are reported and interpreted on the basis of a C2ν symmetry for the molecules. The effects of changes in the electronic structure appear to have a larger influence on the vibrational spectrum than steric or mass effects. The splitting of ν6(D4h) resulting from substitution by L is much larger in the bromide series than in the chloride series and is probably due to π bonding in the complexes. ν1 and ν2 energy changes reflect both a change in bonding and in a smaller mass and steric influence. The compounds Py2AuX3 appear to be trans isomers.