Multiple-decker and ring sandwich formation of manganese-benzene organometallic cluster anions: MnnBzn- (n = 1-5 and 18)

Instantaneous and Phosphine-Catalyzed Arene Binding and Reduction by U(III) Complexes

Neutral arenes such as benzene have never been considered suitable ligands for electropositive actinide cations, yet we find that even simple U^III UX₃ aryloxide complexes such as U(ODipp)₃ bind and reduce arenes spontaneously at room temperature, forming inverse arene sandwich (IAS) complexes X_nU(μ-C₆D₆)UX_m (X = ODipp, n=2, m=3; X = OBMes₂ n=m=2 or 3) (ODipp = OC₆H₃ⁱPr₂-2,6; Mes = 2,4,6-Me₃-C₆H₂). In some of these cases, further arene reduction has occured as a result of X ligand redistribution. These unexpected spontaneous reactions explain the anomalous spectra and reported lack of further reactivity of strongly reducing U^III centers of U(ODipp)₃. Phosphines that are not considered suitable ligands for actinides can catalyze the formation of the IAS complexes. This enables otherwise inaccessible asymmetric and less congested IAS complexes to be isolated and the bonding in this series compared.

An efficient laser vaporization source for chemically modified metal clusters characterized by thermodynamics and kinetics

A laser vaporization cluster source that has a room for cluster aggregation and a reactor volume, each equipped with a pulsed valve, is presented for the efficient gas-phase production of chemically modified metal clusters. The performance of the cluster source is evaluated through the production of Ta and Ta oxide cluster cations, Ta_xO_y⁺ (y ≥ 0). It is demonstrated that the cluster source produces Ta_xO_y⁺ over a wide mass range, the metal-to-oxygen ratio of which can easily be controlled by changing the pulse duration that influences the amount of reactant O₂ introduced into the cluster source. Reaction kinetic modeling shows that the generation of the oxides takes place under thermalized conditions at less than 300 K, whereas metal cluster cores are presumably created with excess heat. These characteristics are also advantageous to yield "reaction intermediates" of interest via reactions between clusters and reactive molecules in the cluster source, which may subsequently be mass selected for their reactivity measurements.