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DFT (B3PW91) and CASSCF calculations have been carried out to study the relative α migratory abilities of H and F in alkyl transition metal complexes. It is shown that the activation energy is considerably lower to migrate H than F, whereas the energies of reaction are similar for the two reactions. A study of the electron configurations and the orbitals describing these configurations shows that the high activation energy for F is due to a 4-electron repulsion between an F lone pair and the occupied Ru=C π orbital. 相似文献
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JOAQUÍN BARBERA´ RAQUEL GIME´NEZ NE´LIDA GIMENO MERCEDES MARCOS MARIA DEL CARMEN PINA JOSE´ LUIS SERRANO 《Liquid crystals》2013,40(6):651-661
Copper and palladium complexes of new salicylaldimines derived from 3,4,5-tridecyloxyaniline, 2,3,4-tridecyloxyaniline and 4-decyloxyaniline have been synthesized and characterized. All the ligands bear four or more aliphatic chains with the aim of inducing columnar mesophases at low temperatures. In particular, metal complexes derived from 4-(3,4,5-tridecyloxybenzoyloxy)-salicyliden-3,4,5-tridecyloxyaninile display rectangular columnar mesophases at (or near) room temperature. These mesophase assignments have been confirmed by X-ray diffraction. A significant decrease of the melting points of the compounds is observed in the tridecyloxyaniline derivatives compared with those of similar complexes derived from mono- or di-decyloxyaniline. 相似文献
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Cowern NE 《Physical review letters》2007,99(15):155903
The energetics of point defects and diffusion in a single crystal is analyzed with respect to stress in overlying or encapsulating layers. The resulting theory subsumes previous formulations of pressure and stress effects on diffusion. A key prediction is that stress on the overlayer side of the crystal boundary perturbs point defect concentrations in the underlying crystal. The effect can occur without significant strain in the crystal itself. The theory is compared with available published data on diffusion in silicon under thin strained overlayers. 相似文献