Reactivities of Metallocarbohedrenes: Nb8C12+

A compact supersonic source is employed with a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer to generate and investigate the metallocarbohedrene, Nb8C12+. Nb8C12+ reacts with water and alcohols via sequential attachments and dehydrogenations leading to the initial truncation products Nb8C12(OR)4+ (R = H, CH3, C2H5, C4H9). Also, Nb8C12+ reacts with NH3 via sequential attachments to produce the initial truncation product Nb8C12(NH3)4+. Nb8C12L5-8+ peaks for ammonia and alcohols are also observed, but they grow in slowly. A measurement of the relative rate constants for the sequential addition reactions of NH3 confirms that addition of the fifth NH3 is at least an order of magnitude slower than the first four attachments. In reactions with acetonitrile and benzene, a maximum of four attachments of these ligands is observed. Sequential halide abstractions with CH3X yield Nb8C12Xn+ truncating at n = 4 for X = Cl and n = 5 for X = Br and I. The “titration” results and the relative rate co...