Configurations of some complexes of rhenium, ruthenium, osmium, rhodium, iridium, and platinum halides with mono(tertiary phosphines) and mono(tertiary arsines)

Abstract

The far-i.r. spectra and, where appropriate, the n.m.r. and e.s.r. spectra of the complexes [MX₄L₂][M = Re, Os, Ir, or Pt; X = Cl or Br; L = mono(tertiary phosphine) or mono(tertiary arsine)] and [MX₃L₃][M = Re, Ru, Os, or Ir; X = Cl or Br; L = mono(tertiary phosphine) or mono(tertiary arsine)] are described. The former group generally have trans-configurations and the latter meridional.

The structural configurations of the complexes with t_2g⁴ metal electron configurations are reliably determined by ¹H n.m.r. spectral measurements. These have shown that the complexes [ReCl₃(PR₃)₃] have mer-configurations and the complexes [OsCl₄(PR₃)₂] probably have trans-configurations. For complexes with t_2g⁵ configurations only broad ¹H n.m.r. spectra were observed, which, except for [RuCl₃(PMe₂Ph)₃], were of no use for structural assignments. However, e.s.r. spectral measurements have confirmed the suggested configurations for the t_2g⁵ complexes.

Far-i.r. studies in the solid state have in general supported the above configurations but are not definitive, especially where complexes of transition elements of the Third Period are concerned.