Electronic Features

After briefly introducing the main electronic features of CNTs (Sec. 2) and some general aspects of electronic conduction and transmission (Sec.. 1), we will show how complex electrical measurements to perform on such tiny entities are (Sec. 4). Then we will present the main experimental results obtained on the electrical resistivity of MWCNT and SWCNT and the very recent data relative to the thermopower of SWCNT bundles (Sec. 5). We will also discuss the effect of intercalation on the electrical resistivity of SWCNT bundles (Sec. 6). Finally, we will present some potential applications (Sec. 7). 

Identify the thermodynamie enolate for each system shown above (2-pentanone enolate A and B 2-methylcyclopentanone enolate A and B decalinone enolate A and B). Also, compare eleetrostatic potential maps for eaeh pair of enolates. What struetural and/or electronic features, if any, appear to dictate which enolate is favored ... 

Since the discovery of buckminsterfullerene (C o) [85NAT(318)162] and other fullerenes (Cig. C70), these molecules have been intensely studied, both experimentally and theoretically. Likewise, several reports on heterofullerenes containing heteroatoms such as nitrogen and boron have appeared (91JPC4948 91JPC10564). The incorporation of heteroatoms is expected to modify the structural and electronic features of these structures, and have thus attracted some interest. 

Mechanical Fuze. Any fuze which depends for its arming and functioning on events primarily of a mechanical nature. Fuzes may consist of a combination of mechanical and electronic features. Proximity fuzes may contain a mechanical delayed arming device mechanical fuzes may be functioned by electrical energy from a piezoelectric element. The classification is dependent upon which features are predominant... 

Perturbation of structural, vibrational, and electronic features of the catalytic center by interaction with probe molecules is the most important experimental approach for understanding the accessibiUty and the reactivity of the site itself. The understanding of the system increases enormously if the experimental results are interpreted on the basis of accurate ab initio modeling. These general statements of course also hold for TS-1 [49,52,64,74-77]. Unfortunately, we do not have the space to enter into a discussion of the abim-dant computational literature published so far on TS-1 catalyst in particular and on titanoshlcates in general. The reader can find an excellent starting point in the Uterature quoted in [49,52,64,74-77,88]. 

A similar argument can be made for electronic features such as electron density, polarization and polarizability. These are critically dependent on the ionization state of the molecule, but the conformahonal state is also highly influential. One highly approximate yet useful reflection of electron density is afforded by the polar surface area (PSA), a measure of the extent of polar (hydrophilic) regions on a molecular surface (see Chapter 5). 

The isoelectronic relationship has been applied to the vanadium complex with hydrotris(pyrazolyl)borato ligand, which possesses the same electronic features as the Cp ligand thus the combination of complex VCl2(NAr)Tp (158) (Ar = 2,6-diisopropylphenyl, Tp = hydrotris(3,5-dimethylpyrazolyl) borate) with MAO was reported to catalyze the polymerization of ethylene (at atmospheric pressure) and propylene (at 7 bar), giving polyethylene (14kg/mol-h, Mw = 47000, Mw/Mn = 3.0) and polypropylene (1 kg/mol h, Mw = 3800, Mw/Mn = 2.0), respectively [256]. 

We have shown in this chapter that the major electronic features that determine the spin dynamics of SIMs based on lanthanides can be directly correlated with the local coordination environment around the 4f metal ions. By using an effective point-charge model that accounts for covalent effects, we have shown that the splitting of the ground state,/, of the lanthanide into Mj sublevels, caused by the influence of the CF created by the surrounding ligands, is consistent with... 

In a continuous effort to circumvent the problem of poor solubility and tune the steric effects and electronic features of Pcs, several effective strategies have been developed. As a result, in recent years many neutral Pcs containing substituents at peripheral a or p positions, or in the axial direction, as well as ionic and sandwich-type Pcs have been synthesized and their single-crystal structures resolved by X-ray diffraction analysis [15-24], It therefore appears necessary to give a relatively comprehensive overview of the new progress in Pc chemistry. In this chapter, we summarize recent research results on the synthesis, crystal structures, and various physical properties of monomeric Pc compounds. 

A.B.P. Lever, York University Most model photocatalysts undergo electron transfer reactions via their spin triplet states. You point out that there are advantages to using the spin singlet state for electron transfer as exemplified by chlorophyll. What kind of structural or electronic features should be built into model photocatalysts to favour use of their spin singlet states for electron transfer quenching ... 

Based on structural, vibrational, and electronic features, C.-T. adducts of S-donor molecules with I2 (the most numerous) were classified in three categories 25 28 (i) Weak or medium weak characterised by a mutual perturbation... 

General Structural Features. The general structure of halfsandwich ruthenium(II)-arene complexes is shown in Fig. 12. The structural, stereochemical and electronic features of metal-arene complexes have been discussed (63). A typical piano-stool geometry consists of an rj6-arene occupying three coordination sites of the pseudo-octahedral complex, leaving the three legs X, Y, and Z available for coordination. The sites X and Y can be taken up by two monodentate ligands, but are more commonly... 

B. Electronic Features and Structural Principles of Molecular Main Group Metal Pnictides... 

In contrast to magnesium phosphandiides, analogous tin(II) derivatives possess more covalent metal-phosphorus bonds. This basic difference is also apparent for dilithium versus dicopper(I) phosphandiides (see Section II and III). It is, therefore, interesting to assess the structural and electronic features of such species in a similar way. To date, only three tin(II) phosphandiide derivatives have been prepared... 

A more widely applied approach to modifying the terpyridine system so as to reduce the field has been to replace one or more of the pyridine rings with five-membered rings. The effects of replacement are much more pronounced for the central ring, because of the steric and electronic features mentioned above, and the [Fe N6]2+ derivative of l,3-bis(pyridin-2-yl)pyra-zole 47, for example, is high spin [64]. This effect is revealed further by the drastically different properties of the [Fe N6]2+ derivatives of the isomeric tridentate ligands 2,4-bis(pyridin-2-yl)thiazole 48 (Dq(Ni2+) 1125 cm-1) and 6-(thiazol-2-yl)-2,2/-bipyridine 49 (Dq(Ni2+) 1230 cm-1). 

An analysis of the most significant homogeneous catalytic systems reported in the literature reveals a structural variety for Pd which is not found for Pt. In fact, although in most cases Pd is incorporated into the (pre)catalyst as divalent ion, active Pd(0) -catalysts have also been reported. By contrast, Pt(0) -catalysts are a rarity. Moreover, Pd complexes containing mono-, di-, tri-, and even tetra-dentate ligands have found application as hydrogenation catalysts, and often their activity and selectivity is governed by the steric and electronic features of... 

Van Huis and Schaefer [8] found that CIO4 has a minimum electronic energy structure of C2v symmetry in contrast with an experimental assignment from infrared spectra by Grothe and Willner [9]. These authors arrived at C31, as the appropriate symmetry group for CIO4 in a neon matrix. The continued interest in the perchlorate radical has prompted the present small study of its electronic features and bonding characteristics. 

---