Self-Assembled Chloro-Bridged (Arene)ruthenium Metallo-Prisms: Synthesis and Molecular Structure of Cationic Complexes of the Type [Ru6(η6-arene)6(μ3-tpt-κN)2(μ-Cl)6]6+(tpt = 2,4,6-tris(pyridinyl)-1,3,5-triazine)

Abstract

Cationic (arene)ruthenium-based hexanuclear complexes with trigonal-prismatic structures have been synthesized in good yield by self-assembly of only two components: the dinuclear (arene)ruthenium complexes [Ru(η6-arene)(μ-Cl)Cl]2 (arene = p-PriC6H4Me, C6Me6) react in water with 2,4,6-tris(pyridinyl)-1,3,5-triazine (tpt) derivatives in the presence of AgO3SCF3 to form hexanuclear cations of the general formula [Ru6(η6-arene)6(μ3-tpt-κN)2(μ-Cl)6]6+. In the presence of 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine (4-tpt) the prismatic cations [Ru6(η6-p-PriC6H4Me)6(μ3-4-tpt-κN)2(μ-Cl)6]6+ (3) and [Ru6(η6-C6Me6)6(μ3-4-tpt-κN)2(μ-Cl)6]6+ (4) have been isolated as the triflate salts, whereas with 2,4,6-tris(pyridin-3-yl)-1,3,5-triazine (3-tpt) [Ru6(η6-p-PriC6H4Me)6(μ3-3-tpt-κN)2(μ-Cl)6]6+ (7) and [Ru6(η6-C6Me6)6(μ3-3-tpt-κN)2(μ-Cl)6]6+ (8) have been obtained and isolated as the triflate salts. In all cases, the neutral intermediates initially formed prior to the addition of silver triflate have been isolated and characterized as well: [Ru3(η6-p-PriC6H4Me)3(μ3-4-tpt-κN)Cl6] (1), [Ru3(η6-C6Me6)3(μ3-4-tpt-κN)Cl6] (2), [Ru3(η6-p-PriC6H4Me)3(μ3-3-tpt-κN)Cl6] (5), and [Ru3(η6-C6Me6)3(μ3-3-tpt-κN)Cl6] (6), respectively. In the case of a trigonal-prismatic hexacation containing p-cymene and 3-tpt ligands, the NMR spectra reveal a mixture of the two isomers 7a and 7b, the formation of which can be rationalized by molecular modeling. The single-crystal structure analyses of [Ru6(η6-p-PriC6H4Me)6(μ3-4-tpt-κN)2(μ-Cl)6][O3SCF3]6 ([3][O3SCF3]6), [Ru6(η6-C6Me6)6(μ3-4-tpt-κN)2(μ-Cl)6][O3SCF3]6 ([4][O3SCF3]6), and [Ru6(η6-C6Me6)6(μ3-3-tpt-κN)2(μ-Cl)6][O3SCF3]6 ([8][O3SCF3]6) reveal strong π stacking interactions between the two tpt subunits of the trigonal prisms.