Theoretical investigations of hydrogen absorption in the A15 intermetallics Ti3Sb and Ti3Ir

Ti3Sb and Ti3Ir adopt the A15 (Cr3Si type) structure and are reported to incorporate hydrogen atoms to an extent, respectively, of Ti3SbH∼3 and Ti3IrH3.8. First-principles electronic structure calculations were performed to identify factors contributing to the difference in maximum hydrogen composition for these two intermetallic compounds. Relative energies and changes in energy densities of states and crystal orbital Hamilton populations upon H insertion in the intermetallic compounds were examined. In both compounds, hydrogen atoms are attracted to [Ti4] tetrahedral interstitial sites over any others. The natures of metal-hydrogen and metalloid-hydrogen bonding and the effects of hydrogen insertion on metal-metal and metal-metalloid bonding have an influence on the maximum hydrogen contents for Ti3Sb and Ti3Ir.

Effect of Tethered, Axial Thioether Coordination on Rhodium(II)-Catalyzed Silyl-Hydrogen Insertion

The effect of tethering a thioether to a rhodium paddlewheel complex are evaluated in diazo-mediated Si–H insertion reactions. This study provides further evidence for the benefits of incorporating thioethers into the rhodium paddlewheel motif. When compared to a non-tethered complex, the <i>in situ </i>carbenoid formation and subsequent Si–H insertion are not impeded by the thioether tether, improves yields by up to 12%, and is more selective for diazo compounds when compared to non-tethered catalysts. Computational modeling of the complexes at the M06-2X/def2-TZVPP level of theory is also presented in order to rationalize the results.

Effect of Tethered, Axial Thioether Coordination on Rhodium(II)-Catalyzed Silyl-Hydrogen Insertion

The effect of tethering a thioether to a rhodium paddlewheel complex are evaluated in diazo-mediated Si–H insertion reactions. This study provides further evidence for the benefits of incorporating thioethers into the rhodium paddlewheel motif. When compared to a non-tethered complex, the <i>in situ </i>carbenoid formation and subsequent Si–H insertion are not impeded by the thioether tether, improves yields by up to 12%, and is more selective for diazo compounds when compared to non-tethered catalysts. Computational modeling of the complexes at the M06-2X/def2-TZVPP level of theory is also presented in order to rationalize the results.