Faculté des sciences

In- and Out-of-Cavity Interactions by Modulating the Size of Ruthenium Metallarectangles

Barry, Nicolas P.E. ; Furrer, Julien ; Therrien, Bruno

In: Helvetica Chimica Acta, 2010, vol. 93, no. 7, p. 1313-1328

Cationic (arene)ruthenium-based tetranuclear complexes of the general formula [Ru4(η6-p-cymene)4(μ-N∩N)2(μ-OO∩OO)2]4+ were obtained from the dinuclear (arene)ruthenium complexes [Ru2... Plus

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    Summary
    Cationic (arene)ruthenium-based tetranuclear complexes of the general formula [Ru4(η6-p-cymene)4(μ-NN)2(μ-OOOO)2]4+ were obtained from the dinuclear (arene)ruthenium complexes [Ru2 (η6-p-cymene)2(μ-OOOO)2Cl2] (p-cymene=1-methyl-4-(1-methylethyl)benzene, OOOO=5,8-dihydroxy-1,4-naphthoquinonato(2−), 9,10-dihydroxy-1,4-anthraquinonato(2−), or 6,11-dihydroxynaphthacene-5,12-dionato(2−)) by reaction with pyrazine or bipyridine linkers (NN=pyrazine, 4,4′-bipyridine, 4,4′-[(1E)-ethene-1,2-diyl]bis[pyridine]) in the presence of silver trifluoromethanesulfonate (CF3SO3Ag) (Scheme). All complexes 4–12 were isolated in good yield as CF3SO3- salts, and characterized by NMR and IR spectroscopy. The host–guest properties of the metallarectangles incorporating 4,4′-bipyridine and (4,4′-[(1E)-ethene-1,2-diyl]bis[pyridine] linkers were studied in solution by means of multiple NMR experiments (1D, ROESY, and DOSY). The largest metallarectangles 10–12 incorporating (4,4′-[(1E)-ethene-1,2-diyl]bis[pyridine] linkers are able to host an anthracene, pyrene, perylene, or coronene molecule in their cavity, while the medium-size metallarectangles 7–9 incorporating 4,4′-bipyridine linkers are only able to encapsulate anthracene. However, out-of-cavity interactions are observed between these 4,4′-bipyridine-containing rectangles and pyrene, perylene, or coronene. In contrast, the small pyrazine-containing metallarectangles 4–6 show no interaction in solution with this series of planar aromatic molecules.