Ambiguous case

From these viewpoints, it is advantageous to use the in-phase spectrum for assigning the resonances in the usual HNCA manner in the first place, thanks to its higher intensity when short tljmax is used. The subspectra can then be used to distinguish between the intra- and interresidual correlations in an ambiguous case.73,76... 

Selected tau values are listed in Table 1. They range from zero for sqp compounds (Class E, for example) to one for tbp compounds (Class A, for example). There is no pattern to how these tau values vary between these two extremes. Rather, there is a continuum of values between 0 and 1. However, a value of 0.50 does not represent an ambiguous case. Even tau values of 0.40 appear more tbp than sqp. An example of this is given in Fig. 15. Also note that electronic factors (the difference in Me or Cl) have no effect, the ligand controls the geometry. 

Whereas several ambiguous cases do indeed still exist, it can be emphasized that they do not cast any uncertainty on the consistency of the majority of data. 

Nomenclature system . The prefix 17 indicates that all unsaturated carbon atoms of the ligand indicated are ir-bonded to the metal atom for complexes in which the metal atom is bonded only to particular carbon atom(s) of a ligand, the total (x) of such metal-bonded atoms is indicated by a superscript (tj ) or, for ambiguous cases, by preceding locant designators, e.g. (tj -allyl), (1-4-Tj-cyclooctatetraene). 

Law Five (ab)c = a(bc) (associative law of multiplication). The two rules are adopted to eliminate ambiguous cases. Rule 1 complex elements must be broken down into their fundamental counterparts and then reacted and rule 2 a reaction in a series of reactions joins the new polymer to the next element on the right. Thus we have Equations 28, 29, 30, 31, and 32. Finally, in conformity with Law Five, we have Equations 33 and 34. The chemical structures associated with Equations 28, 29, and 30 are shown in Figure 2. 

High temperatures favour elimination by gearing up the importance of entropy in the free energy of reaction (AG - AH- TAS). This is a good way of ensuring El in ambiguous cases... 

How many molecules or chemical units are there in the crystallographic asymmetric unit This is a question that is usually easily answerable, but in ambiguous cases must be viewed with caution, as it may significantly affect other phases of the analysis. 

QTAIM provides a definitive answer to the question of whether two atoms are bonded or not even in ambiguous cases [87, 88] and, as a consequence, the molecular graph, i.e., the chemical structure, is readily defined by this theory. Two atoms are bonded if their nuclei are linked in space by a line of maximal electron density termed the bond path [89, 90] (see Fig. 1). A single bond path links the nuclei of chemically bonded atoms irrespective of the mode of the bonding covalent (single or multiple), hydrogen, van der Waals, ionic, metallic, etc. The properties of the eleetron density determined at the point of lowest density along the bond path, where... 

The non-location of hydrogen atoms presents major difficulties both in the determination of coordination numbers for metal atoms, and for correct identification of ligands (e.g. for distinguishing methoxide from methanol). Ambiguous cases were excluded (e.g. M-OCH3 and M-0(H)CH3 both present in a structure in which hydrogen-atom positions were not reported). 

The contours of the absorption bands of each of these models were calculated and compared with the experimentally observed shape of the triply degenerates v3 vibration (asymmetrical CH stretching). For completely free rotation (case III) too large a fraction of the over-all intensity would be found in the wings to agree with the experimental curve. Distinction between case I and case II was ambiguous. Case II seemed to fit the experimental curve a little better on the high-frequency side however, this may be due to overlap of another band. 

Ambiguous cases were reported earlier by Curtin et al. (1962) and by Scherer and Lunt (1966). 

Partition coefficients should be measured with as small amounts of solute as possible to avoid association phenomena in either phase in ambiguous cases the concentration dependence of the partition coefficient should be determined. 

Exceptions and ambiguous cases (e.g., noncontact erection in rats) are more frequent than is commonly recognized. 

Polymerizations can be investigated through the formation of polymer, the disappearance of the monomer, or the formation of another reaction product (e.g., elimination products in polycondensations). In ambiguous cases, all three methods can be applied. 

We use HPLC/MS if the anthocyanin source is a target parameter. The confirmed presence/absence of individual anthoeyanins is a powerful support for the source identity of berry anthoeyanins. In ambiguous cases HPLC/MS can clarify deliberate blending of ddferent berry varieties even at low amounts as detection of anthoeyanins is very sensitive in adequately operated MS instruments. Out of question is the need for HPLC/MS analysis to provide information on anthoeyanins of unknown sources as in those cases HPLC/MS is most convenient way to obtain eonfirmed struetural information. 

The usual strategy in this area has been to calculate both Aj and Aj in ambiguous cases, and then compare A, and k, assuming that they should be similar for a dissociative mechanism, and likewise for A and k. Some results are given in Table 3.23. 

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