Autor: |
Velders, Aldrik H., van der Schilden, Karlijn, Hotze, Anna C. G., Reedijk, Jan, Kooijman, Huub, Spek, Anthony L. |
Zdroj: |
Dalton Transactions; 2004, Vol. 2004 Issue: 3 p448-455, 8p |
Abstrakt: |
The didentate ligand 2-phenylazopyridine azpy can – in theory – give rise to five different isomeric complexes of the type Ruazpy2Cl2, of which three have been known since 1980. The molecular structures of the cis-dichlorobis2-phenylazopyridine rutheniumii complexes α-Ruazpy2Cl2 and β-Ruazpy2Cl2 in which the coordinating pyridine nitrogen atoms are in mutually transand cispositions, respectively, whilst the azo nitrogen atoms are in mutually cispositions were unambiguously determined in the early 1980s. The third isomer, γ-Ruazpy2Cl2, has for two decades, erroneously, been assumed to be the all-transisomer. In a recent communication we have proven that for this γ isomer the chloride ions are indeed in a transgeometry, but the pyridine nitrogen and azo nitrogen atoms of the two azpy ligands are in mutually cisgeometries. In this paper the isolation of a fourth isomer is presented, the hitherto unknown δ-Ruazpy2Cl2. The isomeric structure of δ-Ruazpy2Cl2 has been determined by 1H-NMR spectroscopy and single-crystal X-ray diffraction analysis, and is the all-transisomer. The bisazpy–rutheniumii isomers are of interest because of the pronounced cytotoxicity they exhibit against tumour cell lines and could be very useful in the search for structure–activity relationships of antitumour-active ruthenium complexes, as among the isomers there is a significant difference in activity. It is of paramount importance to have a good understanding of the structural and spectroscopic properties of these complexes, which in this paper are compared and discussed, with a particular emphasis on 1D and 2D 1H NMR spectroscopies. |
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