Encapsulation of Aromatic Molecules in Hexanuclear Arene Ruthenium Cages: A Strategy to Build Up Organometallic Carceplex Prisms with a Dangling Arm Standing Out

Self-assembly of 2,4,6-tris(pyridin-4-yl)-1,3,5-triazine (tpt) subunits with p-cymene (p-PriC6H4Me) or hexamethylbenzene (C6Me6) Ru building blocks and 2,5-dihydroxy-1,4-benzoquinonato (dhbq) or 2,5-dihchloro-3,6-dihydroxy-1,4-benzoquinonato (dchq) bridges affords the triangular prismatic organometallic cations [Ru6(p-PriC6H4Me)6(tpt)2(dhbq)3]6+ ([1]6+), [Ru6(p-PriC6H4Me)6(tpt)2(dchq)3]6+ ([2]6+), [Ru6(C6Me6)6(tpt)2(dhbq)3]6+ ([3]6+), and [Ru6(C6Me6)6(tpt)2(dchq)3]6+ ([4]6+). These hexanuclear cationic cages are isolated in good yield as their triflate salts. The assembly of 1-4 can also be achieved in the presence of large arom. mols. such as pyrene, fluoranthene, benzo[e]pyrene, triphenylene, or coronene to give the corresponding inclusion systems [arom.?1]6+, [arom.?2]6+, [arom.?3]6+, and [arom.?4]6+. The closed proximity of the encapsulated mol. with the different components of the cage and the carceplex nature of these systems are confirmed by 1-dimensional ROESY 1H NMR expts., mass spectrometry, and the single-crystal structure anal. of [pyrene?1][O3SCF3]6 and [benzo[e]pyrene?1][O3SCF3]6. Pyrene can be encapsulated even if it contains a functionalized aliph. substituent; in this case the arom. moiety is included in the cage, while the functionalized side arm stands out. Thus, Me 4-(pyren-1-yl)butanoate (pyrene-R) is encapsulated in 1 to give the carceplex [pyrene-R?1]6+, in which the Me butyrate arm dangles outside the cage while the pyrene moiety is firmly trapped by the metallo-prismatic cation, as demonstrated by 1H NMR expts. and ESI-MS. [on SciFinder(R)]