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Bond Paths (bond + paths)
Selected AbstractsThe Implications of Symmetry of the External Potential on Bond PathsCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2008Erick Cerpa Sixty-coordinate atom? Using a set of molecules in which the number of "bond" paths terminating at an atom is chemically meaningless (an example is shown here); the implications of symmetry of the external potential on the presence of bond paths are discussed. [source] The topologies of the charge densities in Zr and RuACTA CRYSTALLOGRAPHICA SECTION A, Issue 2 2009Travis E. Jones We report on the atomic scale phenomena responsible for the variation of oxygen solubility in Zr and Ru. First-principles calculations reveal that the topologies of the charge densities in these hexagonal close-packed metals are distinct. Neither element was found to possess the topology of the prototype, Mg. There are 12 bond paths terminating at each Ru atom. These are the bonds between nearest neighbors. Only five bond paths terminate at each Zr atom and the Zr atoms are not bound to one another. Instead, they are bonded through non-nuclear maxima. As a result, channels of low charge density that can accommodate oxygen anions are present in Zr. [source] Weak intra- and intermolecular interactions in a binaphthol imine: an experimental charge-density study on (±)-8,-benzhydrylideneamino-1,1,-binaphthyl-2-olACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2009Louis J. Farrugia The charge density in (±)-8,-benzhydrylideneamino-1,1,-binaphthyl-2-ol (1) has been studied experimentally using Mo,K, X-ray diffraction at 100,K, and by theory using density-functional thoery (DFT) calculations at the B3LYP/6-311++G** level. The nature of the weak intramolecular peri -C...N, CH...,, H...H and C(,)...C(,) interactions has been examined by topological analysis using the Quantum Theory of Atoms in Molecules (QTAIM) approach. An analysis of the density ,(r), the Laplacian of the density ,2,(rb) and other topological properties at the bond-critical points were used to classify these interactions. The study confirms the presence of the intramolecular CH..., interaction in (1), which was previously suspected on geometrical grounds. An analysis of the ellipticity profiles along the bond paths unambiguously shows the ,-delocalization between the imine unit and one N -phenyl group. The weak intermolecular interactions in the crystal of (1) were examined experimentally and theoretically through the pairwise interactions of the seven independent dimeric pairs of (1) responsible for the set of unique intermolecular interactions, and also through examination of the Hirshfeld surface dnorm property. The theoretical dimeric-pair calculations used the BLYP-D functional which supplements the exchange-correlational functional with an empirical dispersion term to provide a more accurate determination of the energies for the weak intermolecular interactions. [source] The experimental and theoretical QTAIMC study of the atomic and molecular interactions in dinitrogen tetroxideACTA CRYSTALLOGRAPHICA SECTION B, Issue 5 2009Vladimir G. Tsirelson The atomic and molecular interactions in a crystal of dinitrogen tetraoxide, ,-N2O4, have been studied in terms of the quantum topological theory of molecular structure using high-resolution, low-temperature X-ray diffraction data. The experimental electron density and electrostatic potential have been reconstructed with the Hansen,Coppens multipole model. In addition, the three-dimensional periodic electron density of crystalline ,-N2O4 has been calculated at the B3LYP/cc-pVDZ level of theory with and without the geometry optimization. The application of the quantum theory of atoms in molecules and crystals (QTAIMC) recovered the two types of intermolecular bond paths between O atoms in crystalline ,-N2O4, one measuring 3.094, the other 3.116,Å. The three-dimensional distribution of the Laplacian of the electron density around the O atoms showed that the lumps in the negative Laplacian fit the holes on the O atoms in the adjacent molecules, both atoms being linked by the intermolecular bond paths. This shows that the Lewis-type molecular complementarity contributes significantly to intermolecular bonding in crystalline N2O4. Partial overlap of atomic-like basins created by zero-flux surfaces in both the electron density and the electrostatic potential show that attractive electrostatic interaction exists between O atoms even though they carry the same net formal charge. The exchange and correlation contributions to the potential energy density were also computed by means of the model functionals, which use the experimental electron density and its derivatives. It was found that the intermolecular interactions in ,-N2O4 are accompanied by the correlation energy-density `bridges' lowering the local potential energy along the intermolecular O...O bond paths in the electron density, while the exchange energy density governs the shape of bounded molecules. [source] The Implications of Symmetry of the External Potential on Bond PathsCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2008Erick Cerpa Sixty-coordinate atom? Using a set of molecules in which the number of "bond" paths terminating at an atom is chemically meaningless (an example is shown here); the implications of symmetry of the external potential on the presence of bond paths are discussed. [source] | ||||||||||