Nature and strength of group-14 A-A' bonds.

We have quantum chemically investigated the nature and stability of C-C and Si-Si bonds in RA-AR (A = C, Si; R = H, Me, MePh, MePh, Ph, -Bu) using density functional theory (DFT). Systematic increase of steric bulk of the substituents R has opposite effects on C-C and Si-Si bonds: the former becomes weaker whereas the latter becomes stronger. Only upon going further, from R = Ph to the bulkiest R = -Bu, the RSi-SiR bond begins to weaken.

Methyl Substitution Destabilizes Alkyl Radicals.

We have quantum chemically investigated how methyl substituents affect the stability of alkyl radicals Me H C⋅ and the corresponding Me H C-X bonds (X = H, CH , OH; m = 0 - 3) using density functional theory at M06-2X/TZ2P. The state-of-the-art in physical organic chemistry is that alkyl radicals are stabilized upon an increase in their degree of substitution from methyl View Article and Find Full Text PDF

The Chemical Bond: When Atom Size Instead of Electronegativity Difference Determines Trend in Bond Strength.

We have quantum chemically analyzed element-element bonds of archetypal H X-YH molecules (X, Y=C, N, O, F, Si, P, S, Cl, Br, I), using density functional theory. One purpose is to obtain a set of consistent homolytic bond dissociation energies (BDE) for establishing accurate trends across the periodic table. The main objective is to elucidate the underlying physical factors behind these chemical bonding trends.

Predicting impacts of water conservation with a stochastic sewer model.

Population growth and climate change put a strain on water resources; hence, there are growing initiatives to reduce water use. Reducing household water use will likely reduce sewer input. This work demonstrates the use of a stochastic sewer model to quantify the effect water conservation has on sewer hydraulics and wastewater concentration.

Metal-Metal Interactions in Heterobimetallic Complexes with Dinucleating Redox-Active Ligands.

The tuning of metal-metal interactions in multinuclear assemblies is a challenge. Selective P coordination of a redox-active PNO ligand to Au(I) followed by homoleptic metalation of the NO pocket with Ni(II) affords a unique trinuclear Au-Ni-Au complex. This species features two antiferromagnetically coupled ligand-centered radicals and a double intramolecular d(8)-d(10) interaction, as supported by spectroscopic, single-crystal X-ray diffraction, and computational data.