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Near-Monodisperse Ni−Cu Bimetallic Nanocrystals Of Variable Composition: Controlled Synthesis And Catalytic Activity For H2 Generation, Yawen Zhang, Wenyu Huang, Susan E. Habas, John N. Kuhn, Michael E. Grass, Yusuke Yamada, Peidong Yang, Gabor A. Somorjai
Near-Monodisperse Ni−Cu Bimetallic Nanocrystals Of Variable Composition: Controlled Synthesis And Catalytic Activity For H2 Generation, Yawen Zhang, Wenyu Huang, Susan E. Habas, John N. Kuhn, Michael E. Grass, Yusuke Yamada, Peidong Yang, Gabor A. Somorjai
Wenyu Huang
Near-monodisperse Ni1−xCux (x = 0.2−0.8) bimetallic nanocrystals were synthesized by a one-pot thermolysis approach in oleylamine/1-octadecene, using metal acetylacetonates as precursors. The nanocrystals form large-area 2D superlattices, and display a catalytic synergistic effect in the hydrolysis of NaBH4 to generate H2 at x = 0.5 in a strongly basic medium. The Ni0.5Cu0.5 nanocrystals show the lowest activation energy, and also exhibit the highest H2 generation rate at 298 K.
A New Twist On Pseudorotation, Theresa L. Windus, Mark S. Gordon, Larry W. Burggraf, Larry P. Davis
A New Twist On Pseudorotation, Theresa L. Windus, Mark S. Gordon, Larry W. Burggraf, Larry P. Davis
Mark S. Gordon
For pentacoordinated structures in a trigonal bipyramidal ar· rangement, Berry1 proposed a "pseudorotation" mechanism whereby two such isomers can interconvert through a tetragonal transition state (TS). This Berry pseudorotation mechanism was demonstrated explicitly for SiH5- by following the MP22/6· 31G(d)3 minimum energy path4 (MEP).
Structure And Stability Of Hexacoordinated Sila Dianions, Mark S. Gordon, Marshall T. Carroll, Larry P. Davis, Larry W. Burggraf
Structure And Stability Of Hexacoordinated Sila Dianions, Mark S. Gordon, Marshall T. Carroll, Larry P. Davis, Larry W. Burggraf
Mark S. Gordon
The structures and stabilities of hexacoordinated silicon-containing dianions SiX6 2- have been investigated by using both ab initio (X= H, F) and semiempirical AMI (X= H, F, OH, Me, Cl) calculations. Both methods predict the hexacoordinated structures to be minima on the potential energy surfaces, although the semiempirical barriers for the reactions SiX6 2- -+ Six5- + x- appear to be rather overestimated based on the ab initio results for X = H, F. The positive charge on the central silicon atom actually increases as the number of ligands increases, and the role of d orbitals on that atom appears …
Gas-Phase And Computational Studies Of Pentacoordinate Silicon, Robert Damrauer, Larry W. Burggraf, Larry P. Davis, Mark S. Gordon
Gas-Phase And Computational Studies Of Pentacoordinate Silicon, Robert Damrauer, Larry W. Burggraf, Larry P. Davis, Mark S. Gordon
Mark S. Gordon
We have demonstrated that a wide variety of pentacoordinate silicon anions (siliconates) should be stable and can be prepared by combining the predictive powers of MNDO and ab initio computational methods and the flowing afterglow (FA) experimental technique. MNDO has been used to compute the anion affinities of 91 siliconates; all but five of these are predicted to be stable with respect to the loss of an anion. Twenty-four siliconates, most of them previously unreported, have been prepared and studied in the FA. The MNDO predictions were, in general, consistent with the experimental results and with trends previously reported by …
Thermal Decomposition Of Silane, Mark S. Gordon, David R. Gano, J. Stephen Binkley, Michael J. Frisch
Thermal Decomposition Of Silane, Mark S. Gordon, David R. Gano, J. Stephen Binkley, Michael J. Frisch
Mark S. Gordon
The essential features of the potential energy surface for the thermal decomposition of silane have been calculated with extended basis sets, augmented by correlation corrections. It is predicted that the transition state for the molecular elimination lies 56.9 kcaljmol above silane. For the reverse reaction, the transition state is less than 2 kcal/mol above the separated fragments, silylene and molecular hydrogen, but 4.8 kcal/mol above a long-range potential well. In the latter, the silylene-H2 separation is 1.78 A, and the bond in H2 has stretched by more than 0.05 A. This indicates a significant electronic interaction between the fragments even …
Decomposition Rates, Synthesis, And Spectral Properties Of A Series Of Alkyl Hyponitrites, Craig A. Ogle, Steve W. Martin, Michael P. Dziobak, Marek W. Urban, G. David Mendenhall
Decomposition Rates, Synthesis, And Spectral Properties Of A Series Of Alkyl Hyponitrites, Craig A. Ogle, Steve W. Martin, Michael P. Dziobak, Marek W. Urban, G. David Mendenhall
Steve W. Martin
A number of trans-alkyl hyponitrites (RON=NOR) were synthesized and characterized. At 66.1 f 0.1 "C in isooctane and with millimolar to micromolar concentrations first-order kinetics were observed with half-lives (min) of 12.8 f 0.2 (CHJ, 32.3 f 1.1 (2-C3H7), 15.0 1 0.3 (cyclohexyl), 25.2 i 1.2 (tert-butyl), 18.3 f 0.3 (tert-pentyl), 3.0 f 0.1 (benzyl), 11.2 f 0.5 (2-phenylethyl), and 5.5 f 0.3 (1-phenylethyl). The rate constants were concentration independent and showed little change with changes in solvent polarity or viscosity. Ultraviolet, magnetic resonance, infrared, and mass spectra for the new hyponitrites are reported. Most of the hyponitrites were highly …
Synthesis Of Peroxyacetyl And Peroxyaroyl Nitrates. Complexation Of Perqxyacetyl Nitrate With Benzene, Tina M. Kravetz, Steve W. Martin, G. David Mendenhall
Synthesis Of Peroxyacetyl And Peroxyaroyl Nitrates. Complexation Of Perqxyacetyl Nitrate With Benzene, Tina M. Kravetz, Steve W. Martin, G. David Mendenhall
Steve W. Martin
Convenient procedures are given for the condensed-phase synthesis Of peroxyacetyl nitrate (PAN), peroxybenzoyl ni- sponding peracid% sulfuric acid, and sodium nitrate- The compounds of considerable interest because of their physio- logical and action in polluted atmospheres (1-4). Samples of such compounds are routinely needed for cali- several syntheses have been published (I, 5-8). The procedure of Louw et al. (5) is particularly convenient because the re- corrosive reagents are required. trate, and m-chloroperoxybenzoyl nitrate from the corre- position of the ‘H NMR signal from peroxyacetyl nitrate in CC14-benzene mixtures depended on the solvent composition benzene, with K,, = 0.095 at …