Merck

Performance of PNOF6 for Hydrogen Abstraction Reactions.

The journal of physical chemistry. A (2015-06-13)
Xabier Lopez, Mario Piris, Fernando Ruipérez, Jesus M Ugalde
ABSTRACT

Radical formation through homolytic X-H bond cleavage in LiH, BH, CH4, NH3, H2O, and HF is investigated using natural orbital functional theory in its recent PNOF6 implementation, which includes interelectron-pair correlation, and the results are compared to those of the PNOF5 level of theory, CASSCF wave function methods, and experimental data. It is observed that PNOF6 is able to improve the estimation of the corresponding dissociation energies (De) with respect to PNOF5. When PNOF6 is combined with a better description of the electron pair, through the use of an extended number of coupled orbitals, we obtain further improvements of these quantities. The convergence of the corresponding De values with the number of coupled orbitals is also discussed, finding that a proper convergence of the results is attained with three orbitals. Next, we apply PNOF6 and its improved version PNOF6(3) to describe the thermodynamics of C-H homolytic bond cleavage for a data set of 20 organic molecules in which the C-H bond is broken in the context of different chemical environments. Finally, the radical stabilization energies obtained for such a general data set are compared with the experimental data, demonstrating that the inclusion of interelectron-pair correlation in natural orbital functional theory as in PNOF6 gives a resonable description of radical stability, especially as electron pair description is improved.

MATERIALS
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Carbon - Vitreous, foil, 25x25mm, thickness 0.5mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 1.0mm, glassy carbon
Carbon - Vitreous, foam, 275x330mm, thickness 3.2mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, rod, 200mm, diameter 7.0mm, glassy carbon
Carbon - Vitreous, foil, 100x100mm, thickness 1.0mm, glassy carbon
Carbon - Vitreous, foil, 25x25mm, thickness 4.0mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 10mm, glassy carbon
Carbon - Vitreous, rod, 100mm, diameter 5.0mm, glassy carbon
Carbon - Vitreous, foil, 10mm disks, thickness 0.2mm, glassy carbon
Carbon - Vitreous, rod, 100mm, diameter 3.0mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 3.0mm, glassy carbon
Carbon - Vitreous, foil, 8x8mm, thickness 0.5mm, glassy carbon
Carbon - Vitreous, foam, 150x150mm, thickness 2.5mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, foil, 10x10mm, thickness 4.0mm, glassy carbon
Sigma-Aldrich
Carbon nanofibers, graphitized, platelets(conical), >98% carbon basis, D × L 100 nm × 20-200 μm
Sigma-Aldrich
Methane-12C, 13C-depleted, 99.9 atom % 12C
Sigma-Aldrich
Carbon nanofibers, graphitized (iron-free), composed of conical platelets, D × L 100 nm × 20-200 μm
Carbon - Vitreous, tube, 100mm, outside diameter 10mm, inside diameter 3mm, wall thickness 3.5mm, glassy carbon
Carbon - Vitreous, foam, 300x300mm, thickness 20mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, rod, 5mm, diameter 3.0mm, glassy carbon
Carbon - Vitreous, tube, 50mm, outside diameter 10mm, inside diameter 3mm, wall thickness 3.5mm, glassy carbon
Carbon - Vitreous, foil, 50x50mm, thickness 1.0mm, glassy carbon
Carbon - Vitreous, rod, 100mm, diameter 7.0mm, glassy carbon
Carbon - Vitreous, foam, 275x330mm, 0.05g.cmué, porosity 96.5%, 24 pores/cm
Carbon - Vitreous, foil, 50x50mm, thickness 4.0mm, glassy carbon
Carbon - Vitreous, foil, 10x10mm, thickness 1.0mm, glassy carbon
Carbon - Vitreous, foil, 100x100mm, thickness 6.0mm, glassy carbon
Carbon - Vitreous, rod, 200mm, diameter 5.0mm, glassy carbon
Carbon - Vitreous, foam, 300x300mm, thickness 30mm, bulk density 0.05g/cm3, porosity 96.5%
Carbon - Vitreous, foam, 150x150mm, thickness 3.2mm, bulk density 0.05g/cm3, porosity 96.5%