Steric and Electronic Effects in Gold N-Heterocyclic Carbene Complexes Revealed by Computational Analysis.

A computational analysis of a series of cationic and neutral gold imidazolylidene and benzimidizolylidene complexes is reported. The Bond Dissociation Energies of the various ligands in the complexes calculated at the PBE0-D3/def2-TZVP level of theory increase with increasing ligand volume, except for those of complexes containing t-butyl-substituted ligands, which are anomalously low particularly for the benzimidazolylidene species. Atoms in Molecules studies show the presence of a variety of weak intramolecular interactions, characterised by the presence of bond critical points with a range of different properties.

Computational investigation of Au·H hydrogen bonds involving neutral Au N-heterocyclic carbene complexes and amphiprotic binary hydrides.

In this computational study, we investigate the ability of various neutral R-Au-NHC (NHC = N-heterocyclic carbene) complexes [R = H, CH, Cl, OH] to form hydrogen bonds with the amphiprotic binary hydrides NH, HO and HF. Optimized geometries of the adducts calculated at various levels of theory all exhibit Au⋯HX hydrogen bonds. In adducts of complexes containing NHC ligands with α(N)H units, (NH)⋯XH interactions also exist, yielding hydrogen-bonded rings with graph-set notation [Formula: see text] that correspond to pseudo chelates with κC,H coordination.

A comparison of energetic criteria to probe the stabilizing interaction resulting from a bond path between congested atoms.

Four energetic criteria, all rooted in the partitioning of a molecule into atomic basins based on the properties of the electron density, are compared and correlated with the presence of a bond path between two nonbonded atoms in a series of sterically crowded derivatives of the same tetracyclododecane molecule. It was found that there is no correlation between the selected energetic criteria and the existence of a bond path between the congested atoms, nor with the existence of Ehrenfest force, virial, or Coulomb potential paths between those atoms.

The topology of the Coulomb potential density. A comparison with the electron density, the virial energy density, and the Ehrenfest force density.

The topology of the Coulomb potential density has been studied within the context of the theory of Atoms in Molecules and has been compared with the topologies of the electron density, the virial energy density and the Ehrenfest force density. The Coulomb potential density is found to be mainly structurally homeomorphic with the electron density. The Coulomb potential density reproduces the non-nuclear attractor which is observed experimentally in the molecular graph of the electron density of a Mg dimer, thus, for the first time ever providing an alternative and energetic foundation for the existence of this critical point.

Gold setting the "gold standard" among transition metals as a hydrogen bond acceptor - a theoretical investigation.

The Au(i) atom of dimethylaurate (DMA) is shown to behave as a hydrogen-bond acceptor, providing theoretical evidence that it can act as a Lewis base. Calculations at the MP2/aug-cc-pVTZ-pp level of theory confirm that DMA forms hydrogen bonds decreasing in strength from -16.2 kcal mol to -2.

Preparing Gold(I) for Interactions with Proton Donors: The Elusive [Au]⋅⋅⋅HO Hydrogen Bond.

MP2 and DFT calculations with correlation consistent basis sets indicate that isolated linear anionic dialkylgold(I) complexes form moderately strong (ca. 10 kcal mol(-1) ) Au⋅⋅⋅H hydrogen bonds with single H2 O molecules as donors in the absence of sterically demanding substituents. Relativistic effects are critically important in the attraction.

The topology of the Ehrenfest force density revisited. A different perspective based on Slater-type orbitals.

The topology of the Ehrenfest force density was studied with Slater-type orbitals (STO). At larger distances from the nuclei, STOs generate similar artefacts as noticed before with Gaussian-type orbitals. The topology of the Ehrenfest force density was found to be mainly homeomorphic with the topology of the electron density.

On the structure and bonding of first row transition metal ozone carbonyl hydrides.

Model complexes of the general form M(CO)m(H)n(O3) (m = 1-5, n = 0 or 1) between ozone and the transition metals Ti to Cu were studied by density functional theory (DFT) calculations. The CDA charge decomposition method was used to analyze the interaction between the metal atom and the ozone ligand in terms of the traditional donation-back-donation mechanisms. Information about bond strengths was extracted from an analysis of the electron density in terms of the theory of atoms in molecules (AIM).

Deviation from tetrahedral geometry in Me(2)GeCl(2): crystal structure of a model compound and insight from ab initio calculations.

The molecular structure of Me(2)GeCl(2), and the value of the C-Ge-C angle in particular, was studied by ab initio quantum calculations to examine the deviation of this molecule from ideal geometry in the gas phase and in the crystalline state. The results show that, in the crystal, intermolecular interactions do have a large influence on the geometry of the molecule. An experimental value of 121.