Inclusion of neutral and anionic guests within the cavity of pi-metalated cyclotriveratrylenes

Treatment of the chloride bridged species [{M(L)Cl(mu-Cl)}(2)] (M = Ru, L = 4-MeC(6)H(4)CHMe(2), C6H6, or C(6)Me(6); M = Ir, L = C(5)Me(5)) with silver salts AgX (X = BF4, CF3SO3, CF3CO2 etc.) followed by reflux with the bowl-shaped macrocycle cyclotriveratrylene (CTV) results in the clean formation of mono-, di-, and trimetallic CTV complexes [{M(L)}(n)(CTV)]X(2n) (n = 1, 2, 3). Further salts (X = ReO4-, I-) may be generated by anion metathesis. All three types of complex display novel host-guest properties. In the case of the monometallic hosts the disruption of the characteristic columnar packing mode of the CTV, a result of the presence of the metal center, leads to the inclusion of neutral and anionic guest species (NO(2)Me, Et(2)O, H{CF3CO2}(-)(2), etc.) within the CTV cavity. For complexes where n = 2 or 3 the inclusion of anionic guests is invariably observed. The extent of anion binding has been established by means of X-ray crystal structure determinations upon various di- and trimetallic species containing BF4-, CF3SO3-, or ReO4-, by radiotracer analysis in solution using (TCO4-)-T-99m and (ReO4-)-Re-188, and by cyclic voltammetry. The trimetallic complex [{Ir(Cp*)](3)(CTV)] [BF4](6) (9a) in particular exhibits F ... C-CTV contacts as short as 2.78(3) Angstrom. The dimetallic host [{Ru(eta(6)-4-MeC(6)H(4)CHMe(2))}(2)(eta(6):eta(6)-CTV)](4+) (4) is shown to have a specific affinity for large tetrahedral anions and will selectively extract both (TCO4-)-T-99 and ReO4- from aqueous solution, even in the presence of a large excess of Cl-, CF3SO3-, NO3-, SO42-, and to some extent ClO4-.