Template-Directed Synthesis of Hexanuclear Arene Ruthenium Complexes with Trigonal-Prismatic Architecture Based on 2,4,6-Tris(3-pyridyl)triazine Ligands

Cationic arene ruthenium metalla-prisms of the general formula [Ru-6(p-cymene)(6)(3-tpt)(2)-(OO boolean AND OO)(3)](6+) (3-tpt = 2,4,6-tris(3-pyridyl)-1,3,5-triazine; OO boolean AND OO = 5,8-dioxido-1,4-naphthoquinonato [1](6+) or 6,11-dioxido-5,12-naphthacenedionato [2](6+)) have been obtained from the corresponding dinuclear arene ruthenium complexes [Ru-2(p-cymene)(2)(OO boolean AND OO)Cl-2] by reaction with 3-tpt, silver trifluoromethanesulfonate in the presence of an aromatic molecule (1,3,5-tribromobenzene, phenanthrene, pyrene, or triphenylene) that acts as a template. While the large template molecule triphenylene is permanently encapsulated in the metalla-prisms to give the complexes [triphenylene subset of 1](6+) and [triphenylene subset of 2](6+), 1,3,5-tribromobenzene can be removed in toluene, thus leaving the empty cages [1](6+) and [2](6+), which are isolated as their trifluoromethanesulfonate salts. In the case of the metalla-prism connected by the 5,8-dioxido-1,4-naphthoquinonato bridging ligands, the NMR spectrum reveals two isomers, 1a and 1b, the formation of which can be rationalized by means of multiple NMR experiments (one-dimensional, two-dimensional, ROESY, and DOSY). The empty and filled metalla-prisms, [1](6+), [2](6+), [template subset of 1](6+), and [template subset of 2](6+), have been characterized by NMR, UV-vis, and IR spectroscopy. The slow exchange processes of a guest molecule moving in and out of the cavity of cages [1](6+) and [2](6+) have been studied in solution with phenanthrene and pyrene. One-dimensional exchange spectroscopic (1D EXSY) measurements show that [phenanthrene subset of 1](6+) is in a faster exchange regime than [phenanthrene subset of 2](6+) and that phenanthrene is more easily exchanged than pyrene in cages [1](6+) and [2](6+), all observations being consistent with the portal size of the cages.