Bowl vs saddle conformations in cyclononatriene-based anion binding hosts

The synthesis of organometallic complexes [{Ru(p-MeC6H4CHMe2)}(n)(C21H24S3)][CF3SO3](2n) (n = 1, 6; n = 2, 7) and [{Ir(C5Me5)}(2)(C21H24S3)][CF3SO3](4) (9) based upon the trimeric macrocycle cyclotris(dimethylthiophenylene) (4) is reported. A saddle conformation is identified for the free Ligand 4 and complexes 6 and 9 by X-ray crystallography. The anion complexation behavior of complex 9 is compared with the related cyclotriveratrylene complex [{Ru(p-MeC6H4CHMe2)}(2)(C27H30O6)][CF3SO3](4), which possesses a bowl-shaped conformation, by H-1 NMR titration studies in a variety of solvents. While host 2 displays a significant affinity for halides with binding constants of up to 1.25(7) x 10(3) M-1 in nitromethane solution, the absence of a molecular cavity in 9 results in very little specific anion affinity. The 1,3-alternate calix[4]arene complex [{Ru(eta(6)-p-MeC6H4CHMe2)}(2)(eta(6):eta(6)-C40H48)][BF4](4) is (11) is also reported and shown to bind anions in an unusual C-H anion hydrogen-bonding fashion by X-ray crystallography and H-1 NMR.