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

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 t2g4 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 t2g5 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 t2g5 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.