Host–Guest Chemistry in the Hexanuclear (Arene)ruthenium Metalla‐Prismatic Cage [Ru 6 ( p ‐cymene) 6 (tpt) 2 (dhnq) 3 ] 6+

A large cationic triangular metalla‐prism, [Ru 6 ( p ‐cymene) 6 (tpt) 2 (dhnq) 3 ] 6+ ([ 1 ] 6+ ), incorporating ( p ‐cymene)ruthenium building blocks, bridged by 5,8‐dihydroxy‐1,4‐naphthoquinonato (dhnq) ligands, and connected by two 2,4,6‐tri(pyridin‐4‐yl)‐1,3,5‐triazine (tpt) subunits, allows encapsulation of various guest molecules. This cationic cage, isolated as its triflate salt, possesses a portal size smaller than its cavity, thus allowing both, permanent and temporary encapsulation of guest molecules. The host–guest properties of [ 1 ] 6+ have been studied in solution in the presence of planar molecules [phenanthrene, pyrene, (pyren‐1‐ylmethyl)amine, Pt(acac) 2 , triphenylene]. The stability constant of association ( K a ) was estimated by NMR spectroscopy for the following host–guest systems: [pyrene 1 ] 6+ , [phenanthrene 1 ] 6+ and [(pyren‐1‐ylmethyl)amine 1 ] 6+ . All K a values were found to be larger than 2.4 × 10 4 M –1 for these host–guest systems ([D 3 ]acetonitrile, 21 °C). The other two synthesised complexes, [Pt(acac) 2 1 ] 6+ and [triphenylene 1 ] 6+ , were shown to act as carceplexes only.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)