6.2.2. Definition of Effective Properties 3064 6.3. Response Properties to Magnetic Fields 3066 6.3.1. Nuclear Shielding 3066 6.3.2. Indirect Spin−Spin Coupling 3067 6.3.3. EPR Parameters 3068 6.4. Properties of Chiral Systems 3069 6.4.1. Electronic Circular Dichroism (ECD) 3069 6.4.2. Optical Rotation (OR) 3069 6.4.3. VCD and VROA 3070 7. Continuum and Discrete Models 3071 7.1. Continuum Methods within MD and MC Simulations 3072

/pdf/quantum-mechanical-continuum-solvation-models-3edv963g14.pdf

Quantum mechanical continuum solvation models.

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

J. Appl. Cryst.の発刊に際して

Kenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, Jeffrey R. Long

Carbon Dioxide Capture in Metal–Organic Frameworks

The hydrogen bond is the most important of all directional intermolecular interactions. It is operative in determining molecular conformation, molecular aggregation, and the function of a vast number of chemical systems ranging from inorganic to biological. Research into hydrogen bonds experienced a stagnant period in the 1980s, but re-opened around 1990, and has been in rapid development since then. In terms of modern concepts, the hydrogen bond is understood as a very broad phenomenon, and it is accepted that there are open borders to other effects. There are dozens of different types of X-H.A hydrogen bonds that occur commonly in the condensed phases, and in addition there are innumerable less common ones. Dissociation energies span more than two orders of magnitude (about 0.2-40 kcal mol(-1)). Within this range, the nature of the interaction is not constant, but its electrostatic, covalent, and dispersion contributions vary in their relative weights. The hydrogen bond has broad transition regions that merge continuously with the covalent bond, the van der Waals interaction, the ionic interaction, and also the cation-pi interaction. All hydrogen bonds can be considered as incipient proton transfer reactions, and for strong hydrogen bonds, this reaction can be in a very advanced state. In this review, a coherent survey is given on all these matters.

The hydrogen bond in the solid state.

La methode CNDO/2 avec optimisation de l’ensemble des parametres geometriques a ete appliquee avec succes a l’etude de la protonation des enamines. Elle permet d’expliquer d’une maniere satisfaisante l’aspect thermodynamique du probleme : equilibres enamine-imine et sel d’immonium-sel d’enamonium. Elle apporte des renseignements sur le mecanisme de la N-protonation (origine de l’energie d’activation, chemin d’approche du proton). Pour la C-protonation elle montre que ce n’est pas le proton qui se fixe sur le carbone (ni intra ni intermoleculairement) mais une entite protonique differente.

Approche théorique des mécanismes de protonation: I. — Énamines

The crystal and molecular structures of 3(5),4-dimethylpyrazole, C5H8N2, (I), and of 3,4,5-trimethylpyrazole, C6H10N2, (II), have been determined at 200 K In (I) the 4,5-dimethylpyrazole tautomer is present in the solid state and the six independent molecules in the asymmetric unit form trimers via NH⋯N hydrogen bonds related by a pseudo centre of symmetry The asymmetric unit of (II) contains one and a half molecules: these exhibit NH proton disorder and are hydrogen bonded to each other via their respective NH groups to form chains Ab initio calculations at HF and B3LYP/6-31G** levels indicate that the 3,4-dimethylpyrazole tautomer is more stable than the 4,5-dimethylpyrazole tautomer by only approximately 05  kcal  mol−1 (1 kcal mol−1 = 4184 kJ mol−1)

3(5),4-Dimethyl- and 3,4,5-trimethylpyrazole at 200 K. X-ray crystallography and quantum-chemical analysis

Base-catalyzed trimerization of N-cyanomethylazoles under pressure and in solvent-free conditions afforded 4-amino-2,6-bis(azol-1-ylmethyl)-5-(azol-1-yl)pyrimidines (1–3) in 33–67% yields. The structures of these compounds was determined by a combination of NMR techniques and X-ray crystallography. The 4-amino groups show a restricted rotation around the C–N bond; the free energy of activation for this process was determined by variable temperature experiments. In the crystal structure of the pyrazol-1-yl derivative, the amino group shows a distorted planar geometry in both independent molecules and acts as a double hydrogen bond donor towards two of the three pyrazole rings, forming ribbons of R22(10) rings.

José Elguero

Papers

Approche théorique des mécanismes de protonation: I. — Énamines

3(5),4-Dimethyl- and 3,4,5-trimethylpyrazole at 200 K. X-ray crystallography and quantum-chemical analysis

Solvent-free synthesis and structural characterization of azolyl-substituted pyrimidines

Structural study of diarylazoles related to Rimonabant

Azolides: Structural aspects