Electronic cont structure

Fig. 11 Three-dimensional structures of epothilones determined in different environments (O red, S yellow, N dark blue). Top structures of free EpoA determined by X-ray crystallography from dichloromethane/petroleum ether (top left [9 8] (a)) and from methanol/water (top right [143](b)). Bottom structures of EpoA bound to tubulin determined by solution NMR in aqueous medium (bottom left [96]) and by electron crystallography from zinc-stabilized tubulin sheets (bottom right [26]).(a) The crystal structure data have been available from the author to interested research groups since October 1995.(b) H.-J. Hecht, G. Hofle, unpublished results CCDC 241333 and CCDC 241334 contain the crystallographic data of this structure. These data can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retiieving.html (or from the Cambridge Crystallographic Data Centre, 12, Union Road, Cambridge CB2 1EZ, UK fax (+ 44) 1223-336-033 or deposit cede. cam. ac. uk)...

FIGURE 15.12 (cont d). (b) Crystal structure of 1,3,7,9-tetramethyluric acid and pyrene, (c) HOMO/LUMO overlaps for PAH-TNB complexes. Shown are signs of the wave functions (not electronic charge) for the HOMO and LUMO, and the overlap of molecules observed in the crystalline state (as predicted from the HOMO/LUMO overlap of positive with positive wave functions). 

Fig. 18 (cont.). B, One of a complete series of twelve serial sections through the manipulated chromosome, this one at the level of the first half-bivalent s kinetochores. Two chromosomal microtubules are indicated by arrows they lie in the direction of bivalent motion, as does a third microtubule seen in an adjacent section. X80,000. C, A section at the level of the second half-bivalent s kinetochores, which had evinced no motion up to the time of fixation. Neither this nor the adjacent sections disclose any microtubules here, but kinetochore structure (the less electron opaque chromosome material indicated by the arrows) is Identical with that of unmanipulated bivalents. X80,000. (From unpublished studies of Brinkley and Nicklas.)... 

TABLE 6 TR3 X3 Cluster Halides, Structure Types, Cluster-Based Electron (CBE), and Mean Distances (in pm) —Cont d... 

The first band structure calculation for TiC, TiN, and TiO was performed by Bilz (13). He used a simplified linear combination of atomic orbitals (LCAO) method and considered only the M— X bonds as the important ones. From his results he inferred a charge transfer from the metal to the nonmetal atom. A completely opposite point of view was adopted by Costa and Conte (14). These authors ignored the M—X bonds and considered only the M—M bonds. According to their calculations, a transfer of electronic charge from the nonmetal to the metal atom should occur. Lye and Logothetis (15), using optical data to adjust the parameters in their... 

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