Dibridged, Monobridged, Vinylidene-Like, and Linear Structures for the Alkaline Earth Dihydrides BeH, MgH, CaH, SrH, and BaH. Proposals for Observations.

This research reports a search for peculiar monobridged structures of the EH molecules (E = Be, Mg, Ca, Sr, Ba). For BeH and MgH, the monobridged geometry is not an equilibrium but rather a transition state between the vinylidene-like structure and the global minimum HE-EH linear geometry. However, for CaH, SrH, and BaH, this situation changes significantly; the linear structure is no longer the global minimum but lies higher in energy than two other equilibria, the dibridged and monobridged structures.

Investigating the Effects of Basis Set on Metal-Metal and Metal-Ligand Bond Distances in Stable Transition Metal Carbonyls: Performance of Correlation Consistent Basis Sets with 35 Density Functionals.

Density functional theory (DFT) is a widely used method for predicting equilibrium geometries of organometallic compounds involving transition metals, with a wide choice of functional and basis set combinations. A study of the role of basis set size in predicting the structural parameters can be insightful with respect to the effectiveness of using small basis sets to optimize larger molecular systems. For many organometallic systems, the metal-metal and metal-carbon distances are the most important structural features.

Combustion chemistry: important features of the C3H5 potential energy surface, including allyl radical, propargyl + H2, allene + H, and eight transition states.

The C(3)H(5) potential energy surface (PES) encompasses molecules of great significance to hydrocarbon combustion, including the resonantly stabilized free radicals propargyl (plus H(2)) and allyl. In this work, we investigate the interconversions that take place on this PES using high level coupled cluster methodology. Accurate geometries are obtained using coupled cluster theory with single, double, and perturbative triple excitations [CCSD(T)] combined with Dunning's correlation consistent quadruple-ζ basis set cc-pVQZ.

Exploring the effects of H-bonding in synthetic analogues of nickel superoxide dismutase (Ni-SOD): experimental and theoretical implications for protection of the Ni-SCys bond.

Nickel superoxide dismutase (Ni-SOD) is a recently discovered SOD obtained from soil microbes and cyanobacteria that shares no structural or spectroscopic similarities with other isoforms of SOD. The enzyme is found in both the Ni(II) (Ni-SOD(red)) and Ni(III) (Ni-SOD(ox)) oxidation states in "as isolated" preparations of the enzyme from two separate and independently crystallized Streptomyces strains. Ni-SOD contains an unusual and unprecedented biological coordination sphere comprised of Cys-S and peptido-N donors.