Theoretical studies structure

With polyols, the procedure of separating contact from pseudocontact shifts sometimes proves unsatisfactory some of the higher lanthanides give discordant results. - It appears that complexes of these higher lanthanides, that have smaller ionic radii, have different interatomic distances and valency angles, and probably different coordination numbers, even if they have the same structures. Theoretical studies confirmed these differences. It is advisable, therefore, to disregard the higher lanthanides in this procedure. ... 

Over the past 50 years, spectacular advances have been made in X-ray diffraction, nuclear magnetic resonance spectroscopy, and several other techniques for determining structure. Theoretical studies of polymers have also been developing at a rapid pace with faster and more advanced computing capability. There is much interest at the moment in the possibility of using biological molecules such as proteins and DNA as electrical conductors. The possibility... 

For over four decades, interest in the family of cyclic oxocarbon dianions has focused on their aromaticity and molecular structure. Theoretical studies have indicated that aromaticity decreases with increasing ring size, and CeOg possesses only a small degree of aromatic character [47, 51]. Furthermore, while it is firmly established that the... 

Stambuli, J.P., Incarvito, C.D., Buehl, M. and Hartwig, J.F. (2004) Synthesis, structure, theoretical studies, and ligand exchange reactions of monomeric, T-shaped arylpalladium(II) halide complexes with an additional, weak agostic interaction. J. Am. Chem. Soc., 126,1184—94. 

The discovery of perfect geodesic dome closed structures of carbon, such as C o has led to numerous studies of so-called Buckminster fullerene. Dislocations are important features of the structures of nested fullerenes also called onion skin, multilayered or Russian doll fullerenes. A recent theoretical study [118] shows that these defects serve to relieve large inherent strains in thick-walled nested fullerenes such that they can show faceted shapes. 

We do not wish to go into the details of Figure 10. As an illustration of the reliability of the present results we compare, however, in Figure 11, the structure of the measured HCCS spectrum published by Tang and Saito (Fig. 3 of [139]) with the results of the theoretical study. Taking into account the very complex and unusual structure of this kind of spectra, we find the agreement between our ab initio theoretical results and those following from the interpretation of experimental spectra more than satisfactory. While strongly... 

Theoretical methods ranging from the now obsolete HMO studies to ab initio calculations have been used extensively on pyrazoles. Although not emphasized in earlier reviews (66AHC(6)347,67HC(22)l), the most recent publications (B-76MI40402,79RCR289) contain several references to theoretical studies. Some publications related to structural studies are to be found in the following sections, especially in connection with NMR spectroscopy (Section 4.04.1.3.4), UV spectroscopy (Section 4.04.1.3.6), PE spectroscopy (Section 4.04.1.3.9) and tautomerism (Section 4.04.1.5). 

However, the fundamental contribution to the theoretical study of the structure of substituted pyrazoles has been made by Finar 6SJCS(B)725,70JCS(B)1692). Figure 3 shows... 

The successful application of heterocyclic compounds in these and many other ways, and their appeal as materials in applied chemistry and in more fundamental and theoretical studies, stems from their very complexity this ensures a virtually limitless series of structurally novel compounds with a wide range of physical, chemical and biological properties, spanning a broad spectrum of reactivity and stability. Another consequence of their varied chemical reactivity, including the possible destruction of the heterocyclic ring, is their increasing use in the synthesis of specifically functionalized non-heterocyclic structures. 

Another principal difficulty is that the precise effect of local dynamics on the NOE intensity cannot be determined from the data. The dynamic correction factor [85] describes the ratio of the effects of distance and angular fluctuations. Theoretical studies based on NOE intensities extracted from molecular dynamics trajectories [86,87] are helpful to understand the detailed relationship between NMR parameters and local dynamics and may lead to structure-dependent corrections. In an implicit way, an estimate of the dynamic correction factor has been used in an ensemble relaxation matrix refinement by including order parameters for proton-proton vectors derived from molecular dynamics calculations [72]. One remaining challenge is to incorporate data describing the local dynamics of the molecule directly into the refinement, in such a way that an order parameter calculated from the calculated ensemble is similar to the measured order parameter. 

CNTs, or changes of structure or melting point of liquid in nanometric cavities, etc. Many interesting experimental and theoretical studies are in progress on the CNT filling, and the obtained new knowledge will not only be useful for fullerene-related materials field, but also it will illuminate the development of the whole field of nanotechnologies. 

As in previous theoretical studies of the bulk dispersions of hard spheres we observe in Fig. 1(a) that the PMF exhibits oscillations that develop with increasing solvent density. The phase of the oscillations shifts to smaller intercolloidal separations with augmenting solvent density. Depletion-type attraction is observed close to the contact of two colloids. The structural barrier in the PMF for solvent-separated colloids, at the solvent densities in question, is not at cr /2 but at a larger distance between colloids. These general trends are well known in the theory of colloidal systems and do not require additional comments. 

S. Chandrasekar (Chicago) theoretical studies of the physical processes of importance to the structure and evolution of the stars. 

Theoretical study of the effects of molecular structure and solvation on tautomeric equilibria (SCF-MO-PPP)... 

The first systematic theoretical study on dihydro-1,2,4-triazines was recently carried out (98JOC5824) the stabilities of all the possible unsubstituted dihydro-1,2,4-triazines were calculated using various theoretical methods, all reliable calculation methods consistently show that the 2,5-dihydro isomer 98 is the most stable. This is in perfect agreement with the experimental observations all the synthetic methods used for the preparation of dihydro-1,2,4-triazines result in 2,5-dihydro isomer 98, provided the structures of the reactants and the reaction mechanism allow its formation. Thus, although Metze and Scherowsky (59CB2481) claimed the formation of 1,2-dihydro-1,2,4-triazine 92 (R = = Ph) in the reduction... 

The theoretical studies " have been focused on TiSi2. Some attempts, with use of high-symmetry crystal structures, have been made to understand some of the other titanium silicides. This paper deals vith Ti,5Si.3. Because of the crucial interplay between structure and bonding we have studied the proposed stable low-symmetry crystal structure. This will give a better picture of the electronic structure and the bonding properties in this system. An investigation of seven members in the Ti-Si system will be presented in a future publication. ... 

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