Novel Polypyridyl Ruthenium(II) Complexes Containing Oxalamidines as Ligands.
Ruben, M., Rau, Sven, Skirl, A., Krause, K., Görls, Helmar, Walther, D. and Vos, Johannes G.
(2000)
Novel Polypyridyl Ruthenium(II) Complexes Containing Oxalamidines as Ligands.
Inorganica Chimica Acta, 303
(2).
pp. 206-214.
ISSN 0020-1693
The complexes [Ru(bpy)2(H2TPOA)](PF6)2 ⋅ 4H2O, (1); [Ru(Me-bpy)2(H2TPOA)](PF6)2
⋅ 2H2O, (2); [Ru(bpy)2(H2TTOA)](PF6)2 ⋅ 2H2O, (3); [Ru(Me-bpy)2(H2TTOA)](PF6)2 ⋅ 2H2O,
(4) and {[Ru(bpy)2]2(TPOA)}(PF6)2 ⋅ 2H2O, (5) (where bpy is 2,2´bipyridine; Me-bpy is 4,4´-
dimethyl-2,2´-bipyridine; H2TPOA is N, N´, N´´, N´´´- tetraphenyloxalamidine; H2TTOA is
N, N´, N´´, N´´´- tetratolyloxalamidine) have been synthesized and characterized by 1H-NMR,
FAB-MS, infrared spectroscopy and elemental analysis. The X-ray investigation shows the
coordination of the still protonated oxalamidine moiety via the 1,2−diimine unit. The dimeric
compound (5) could be separated in its diastereoisomers (5´) and (5´´) by repeated
recrystallisation. The diastereomeric forms exhibit different 1H-NMR spectra and slightly
shifted electronic spectra. Compared with the model compound [Ru(bpy)3]2+, the absorption
maxima of (1)–(5) are shifted to lower energies. The mononuclear complexes show Ru(III/II)-
couples at about 0.9 V vs SCE, while for the dinuclear complex two well defined metal based
redox couples are observed at 0.45 and 0.65 V indicating substantial interaction between the
two metal centres.