η6-Coordination of the Curved Carbon Surface of Corannulene (C20H10) to (η6-arene)M2+ (M = Ru, Os)

Reactions of [(η6-arene)M(acetone)3]X2 (M = Ru, Os; X = BF4, PF6, or SbF6) with 1 equiv of the curved-surface buckybowl, corannulene (C20H10, 1), in CD3NO2 afford quantitatively the η6-coordinated complexes [(η6-C6Me6)Ru(η6-C20H10)]X2 (3a, X = SbF6; 3b, X = PF6; 3c, X = BF4), [(η6-C6HMe5)Ru(η6-C20H10)](SbF6)2 (4), [(η6-C6EtMe5)Ru(η6-C20H10)](SbF6)2 (5), and [(η6-cymene)Os(η6-C20H10)](SbF6)2 (6). In the solid state, yellow complexes 3−6 are stable in dry air for several months and have all been characterized by their 1H, 13C{1H}, and COSY NMR, mass spectra, elemental analyses, and X-ray diffraction; the corannulene in the complexes is slightly flattened as compared with free corannulene, 1. Even in the presence of excess [(η6-arene)M(acetone)3]X2, it was not possible to add two (η6-arene)M2+ units to 1. The corannulene ligand in 3a is susceptible to nucleophilic attack by phosphines to give a mixture of adducts.