The long-held “shielding cone” model of the through-space NMR shielding effect of a carbon-carbon double bond predicts only the effect of the magnetic anisotropy of the double bond; it ignores other important contributors to the overall shielding. GIAO-SCF and GIAO-MP2 calculations have been performed on a simple model system, methane moved sequentially above ethene or 2-methylpropene. These ca...

Reactions of the vinylidene complexes [M([double bond, length as m-dash]C[double bond, length as m-dash]CH2)(PP)Cp']PF6 with NH3 readily afford the acyclic amino carbene complexes [M{C(Me)NH2}(PP)Cp']PF6 [M(PP)Cp' = Fe(dppe)Cp, Ru(dppe)Cp, Ru(PPh3)2Cp, Ru(dppe)Cp*]. Crystallographic, spectroscopic and computational data support a description of these complexes in terms of a M-{C(Me)[double bond...

In the biologically active title compound, C26H26O5, the pyran ring of the chromene unit adopts a half-chair conformation. The C=C double bond of the propenone unit exhibits a trans conformation and the carbonyl group is syn conformation to the double bond. The dihedral angle between the benzene ring and the benzopyran-one moiety is 31.54 (4)°. The mol-ecular structure is stabilized by an intra...

Grignard reagents (RMgBr: R = Et, p-tolyl) selectively attacked the β-position of the bridgehead double bond of tosylazafulleroid through interaction of Mg with the S[double bond, length as m-dash]O group. The following [5,6] ring closure and C-N bond scission led to aryl/alkyl aminylfullerenes with 1,2-configuration. Tolyl-substituted aminylfullerene was further converted into 1,4-di(p-tolyl)f...

The title compound, C(22)H(24)N(4)O(4)S, adopts a trans configuration with respect to the C=N double bond. A weak intra-molecular C-H⋯N hydrogen bond is observed between the N atom of the C=N double bond and its neighboring phenyl H atom. The crystal structure is stabilized by inter-molecular C-H⋯N hydrogen bonds and C-H⋯π inter-actions.

OBJECTIVES To evaluate the effect of double-application of all-in-one adhesives using the micro-shear bond test. METHODS The occlusal surfaces of extracted human third molars were ground perpendicular to the long axis of each tooth to expose a flat dentin surface. Three commercially available and one experimental bonding system were used in this study: Adper Prompt L-Pop (APL, 3M ESPE), REACT...

The induction of freezing tolerance in bromegrass (Bromus inermis Leyss) cell culture was used to investigate the activity of absisic acid (ABA) analogs. Analogs were either part of an array of 32 derived from systematic alterations to four regions of the ABA molecule or related, pure optical isomers. Alterations were made to the functional group at C-1 (acid replaced with methyl ester, aldehyd...

Monomers in the polymer-based provisional crown and fixed partial denture materials form polymer network as carbon-carbon double bonds are converted to carbon-carbon single bonds during polymerization. This reaction is not complete. There will be a certain amount of monomer remaining in the resin materials. This is influenced by several factors, such as type of monomer, curing temperature, expo...

cycloaddition reaction between c30 and hula-i, 3-diene was studied within the snimework of am i (rhf)level. the reaction involving the double bond between two hexagons and a hexagon and a pentagon, as wellas the cycloaddition products followed by disrotatory ogs s electrocyclic ring openings were considered.thermodynamics parameters and stability energy and innsation state are evaluated in thre...

New Schiff-base compound (E)-4-methoxy-N-(4-hydroxybenzylidene) aniline has been synthesized from the reaction of 4-hydroxybenzaldehyde with 4-methoxyaniline in methanol at 50ºC, and has been characterized by using elemental analysis and FT-IR spectroscopy. The crystal structure of the title compound has been determined by single crystal X-ray diffraction study. The title compound crystallizes ...