The 1H NMR signals of the Ru(III) species present in solution are considerably broadened and shifted by paramagnetism, but they can be used to follow chloride displacement in the trans-[RuCl4Im2]− ion. This anion remains predominant for several hours at room temperature in D2O, but its signals are progressively replaced by those of a monoaqua [RuCl3(D2O)Im2] complex. Over a period of days, two new sets of peaks appear, corresponding to two isomers of [RuCl2(D2O)2Im2]+. The same behaviour is observed for the 1-methyl-and 4-methylimidazole analogues. These reactions can be driven backwards by addition of KCl, but [RuCl4Im2]− is not quantitatively regenerated in solution even for 6 M NaCl. Within several months, the [RuCl2(D2O)2Im2]+ isomers further aquate to a single species [RuCl(D2O)3Im2]2+. In CD3OD, displacement of the first chloride of [RuCl4Im2]− takes place faster, over several hours, but substitution stops at the [RuCl3(CD3OD)Im2] stage. In DMSO, substitution occurs very slowly. The [RuCl3(DMSO)Im2]:[RuCl4Im2]−mixture (1:2) obtained after 12 days starts to show very slow reduction to two Ru(II) species, one of which precipitates as yellow crystals. From X-ray diffraction work (monoclinic, P21/n, a = 9.951, b = 8.564, c = 10.527 Å, β = 92.95°, R = 0.033), the compound was identified as [RuCl2(DMSO-d6)2Im2], where the metal has a trans-trans-trans coordination and the DMSO ligands are S-bonded. Keywords: paramagnetic ruthenium anion, solvolysis, chloro complexes.
13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes