Reactions of phthalazine, quinazoline, 4,7-phenanthroline and 2,3′-bipyridine with ruthenium carbonyl?

Dalton Transactions Pub Date: 2012-04-19 DOI: 10.1039/C2DT30583F

Abstract

The reactions of [Ru3(CO)12] with four aromatic diazines have been studied in THF at reflux temperature. With phthalazine (L1), the compound [Ru3(μ-κ2N2N3-L1)(μ-CO)3(CO)7] (1), which contains an intact phthalazine ligand in an axial position bridging an Ru–Ru edge through both N atoms, is initially formed but it reacts with more phthalazine to give [Ru3(κN2-L1)(μ-κ2N2N3-L1)(μ-CO)3(CO)6] (2), in which a π–π stacking interaction between the aromatic rings of both ligands determines their position in cluster axial sites on the same face of the Ru3 triangle. With quinazoline (HL2), the cyclometalated hydrido decacarbonyl derivative [Ru3(μ-H)(μ-κ2N3C4-L2)(CO)10] (3) is initially produced but it partially decarbonylates under the reaction conditions to give [Ru6(μ-H)2(μ-κ2N3C4-L2)(μ3-κ3-N1N3C4-L2)(CO)19] (4), which results from the displacement of a CO ligand of 3 by the uncoordinated N1 atom of another molecule of 3. With 4,7-phenanthroline (H2L3), the stepwise formation of the cyclometalated derivatives [Ru3(μ-H)(μ-κ2N4C3-HL3)(CO)10] (5) and two isomers of [Ru6(μ-H)2(μ4-κ4N4C3N7C8-L3)(CO)20] (6a, 6b) takes place. In compounds 6a and 6b, two Ru3(μ-H)(CO)10 trinuclear units are symmetrically (C2 in 6a or CS in 6b) bridged by a doubly-cyclometalated 4,7-phenanthroline ligand. With 2,3′-bipyridine (HL4), two products have been isolated, [Ru3(μ-H)(μ-κ2N3′C4′-L4)(CO)10] (7) and [Ru3(μ-H)(μ-κ3N2N3′C2′-L4)(CO)9] (8). While compound 7 contains an N3′C4′-cyclometalated 2,3′-bipyridine, in compound 8 an N3′C2′-cyclometalation is accompanied by the coordination of the N2 atom of the remaining pyridine fragment. The structures of compounds 2, 3, 4, 6a and 8 have been determined by X-ray diffraction crystallography.

Graphical abstract: Reactions of phthalazine, quinazoline, 4,7-phenanthroline and 2,3′-bipyridine with ruthenium carbonyl
Recommended Literature