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Crystal Structural Data (crystal + structural_data)
Selected Abstracts4-Substituted and 4,5-Disubstituted 3,6-Di(2-pyridyl)pyridazines: Ligands for Supramolecular AssembliesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 9 2008Edwin C. Constable Abstract The syntheses by inverse electron demand Diels,Alder reactions and characterization of 28 members of a family of 3,6-di(2-pyridyl)pyridazines, functionalized in the 4- or 4,5-positions are reported. Single crystal structural data are presented for four representative derivatives. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] On the relative stability of cobalt- and nickel-based amidinate complexes against ,-migrationINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 4 2009Jiaye Li Abstract We present a first-principles study on the relative stability of cobalt- and nickel-based amidinate complexes against ,-migration using density functional theory. Factors that influence the reactivity of these compounds were carefully addressed and the calculated molecular structures are in excellent agreement with the available crystal structural data. Reaction energies as well as activation barriers of ,-migration were evaluated. The predicted relative stability of the selected compounds is consistent with experimental observations. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] A new molecular mechanics force field for the oxidized form of blue copper proteinsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 7 2002Peter Comba Abstract A molecular mechanics force field for blue copper proteins has been developed, based on a rigid potential energy surface scan of the CuII/His/His/Cys/Met chromophore, using DFT (B3LYP) calculations and the AMBER force field for the protein backbone. The strain,energy-minimized structures of the model chromophore alone are in excellent agreement with the DFT-optimized structure, and those of the entire set of cupredoxins (five structures are considered) are, within the experimental error limits, in good agreement with the single crystal structural data. However, the structural variation in the computed structures is much smaller than those in the experimental structures. It is shown that, due to the large error limits in the experimental data, a validation of the force field with experimental structural data is impossible because, within the error limits, all experimental structures considered are virtually identical. A validation on the basis of spectroscopic data and their correlation with experimental and computed structural data is proposed, and, as a first example, the correlation of intensity ratios of the charge transfer transitions with a specific distortion mode is presented. The quality of the correlation, using the computed structures, is higher than that with the X-ray structures, and this indicates that the computed structures are meaningful. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 697,705, 2002 [source] Space-demanding intramolecular isomerizations in the solid stateJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 3 2002G. Kaupp Abstract The thermal isomerizations of meso - and rac -3,4-dibromo-1,6-diphenyl-1,6-bis(p -tolyl)-1,2,4,5-hexatetraene (1) to give stereospecifically the 3,4-bis(phenyl- p -tolylmethylene)-1,2-dibromocyclobutenes 3 and 5,+,6 were studied in the solid state using atomic force microscopy (AFM) and interpreted on the basis of known crystal structural data. These isomerizations run to completion in the bulk and include highly space-demanding internal rotations around the central bond. Far-reaching anisotropic molecular movements are detected on the major faces that align the surface features along cleavage planes in the initial phase rebuilding stage. Only one of three identified cleavage planes of meso - 1 is successful, owing to closer interactions of the bromine substituents in the non-used cleavage planes. Thus, very fine details can be correlated and predicted for the occurrence of internal rotations and molecular movements in the crystal lattice. The second stage in these intramolecular isomerizations, the phase transformation, produces very high features up to 100,nm and still parallel to the preferred cleavage plane of meso - 1 but in the,µm range without relation to the initial crystal structure in the case of rac - 1. Copyright © 2002 John Wiley & Sons, Ltd. [source] | ||||||||||