The effect of using a realistic model for the electrostatic forces on the calculated structures of molecular crystals is explored by using atomic multipoles derived from an SCF 6-31G** wave function. This was tested on a wide ranging database of 40 rigid organic molecules containing C, H, N, and O atoms, including nucleic acid bases, nonlinear optic materials, azabenzenes, nitrobenzenes, and simpler molecules. The distributed multipole electrostatic model, plus an empirical repulsion-dispersion potential, was able to successfully reproduce the lattice vectors and available heats of sublimation of the experimental room temperature structure in almost all cases. Scaling the electrostatic energy to allow for the effect of electron correlation on the molecular charge density generally improved the lattice energies and the calculated structures to a lesser extent. However, omitting the anisotropic multipole moments usually gave very poor, sometimes qualitatively wrong structures, emphasizing the sensitivity of these crystal structures to the electrostatic forces. We also investigated the sensitivity of the structures to the empirical repulsion-dispersion potential parameters by attempting to optimize these. Since the experimental structures are mainly reproduced to within the errors that could be attributed to the use of static minimization and rigid molecules, it appears that going beyond the atomic charge model to a realistic electrostatic model is a key development in the modeling of the crystal structures of polar and hydrogen-bonded molecules.

The selective oxidation of methane, the primary component of natural gas, remains an important challenge in catalysis. We used colloidal gold-palladium nanoparticles, rather than the same nanoparticles supported on titanium oxide, to oxidize methane to methanol with high selectivity (92%) in aqueous solution at mild temperatures. Then, using isotopically labeled oxygen (O) as an oxidant in the presence of hydrogen peroxide (HO) we demonstrated that the resulting methanol incorporated a substantial fraction (70%) of gas-phase O More oxygenated products were formed than the amount of HO consumed, suggesting that the controlled breakdown of HO activates methane, which subsequently incorporates molecular oxygen through a radical process. If a source of methyl radicals can be established, then the selective oxidation of methane to methanol using molecular oxygen is possible.

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