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Issue 16, 2006
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Aggregation tendency and reactivity toward AgX of cationic half-sandwich ruthenium(II) complexes bearing neutral N,O-ligands

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Abstract

The aggregation tendency of complexes [Ru(η6-cymene)(N,O)Cl]X [N,O = 2-benzoylpyridine (2-bzpy), 1, and 2-acetylpyridine (2-acpy), 2, X = BPh4 or PF6] has been studied by means of PGSE NMR experiments. It was found that complexes with PF6 as counterion are mainly present in CD2Cl2 as ion pairs at low concentration, as a mixture of ion triples and free anions at medium concentration and as ion quadruples at elevated concentration. 19F, 1H-HOESY NMR experiments revealed that in ion triples and ion quadruples two cationic Ru-units pair up. Consistently, in the solid-state structure of 1PF6, determined through X-ray single-crystal investigation, two cationic Ru-units are held together by an intermolecular π–π stacking interaction between the pyridyl rings. Complexes having BPh4 as counterion are only present in solution as even aggregates, namely ion pairs at low concentration and ion quadruples at elevated concentration. In such a case a counteranion bridges two cationic Ru-units as observed in the solid-state structure of 1BPh4. The reactivity of complexes 1–2 toward AgX salts has been investigated in different solvents. Bicationic [Ru(η6-cymene)(N,O)(MeCN)]X2 (N,O = 2-bzpy, 3, and 2-acpy, 4) and [Ru(MeCN)4(N,O)]X2 (N,O = 2-bzpy, 5, and 2-acpy, 6) complexes were obtained by the reaction of 1 and 2 with AgX in the presence of three equivalents of acetonitrile or in acetonitrile, respectively. The reaction of 1 with AgPF6 in acetone afforded complex [Ru(η6-cymene)(N,O,O)]PF6 (7, where N,O,O = 4-alcoxide-4-phenyl-4-(pyridin-2-yl)butan-2-one) from the C–C coupling of a deprotonated methyl group of the coordinated acetone and the C[double bond, length as m-dash]O moiety of 2-bzpy ligand.

Graphical abstract: Aggregation tendency and reactivity toward AgX of cationic half-sandwich ruthenium(ii) complexes bearing neutral N,O-ligands

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Publication details

The article was received on 07 Oct 2005, accepted on 05 Jan 2006 and first published on 18 Jan 2006


Article type: Paper
DOI: 10.1039/B514269E
Citation: Dalton Trans., 2006, 1963-1971
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    Aggregation tendency and reactivity toward AgX of cationic half-sandwich ruthenium(II) complexes bearing neutral N,O-ligands

    D. Zuccaccia, G. Bellachioma, G. Cardaci, C. Zuccaccia and A. Macchioni, Dalton Trans., 2006, 1963
    DOI: 10.1039/B514269E

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