Multiplet complex, structure

It has also been mentioned that TOCSY results in the net transfer of in-phase magnetisation, meaning the cancellation effects from antiphase multiplet fine-structure associated with COSY are not a feature of TOCSY. Such cancellation can be problematic for molecules that posses large natural linewidths, for example (bio)-polymers, but may also prevent the observation of COSY peaks in the spectra of small molecules that have complex multiplet structures which may cancel under conditions of poor digital resolution. In these cases the TOCSY experiment may be viewed as the more sensitive option because of the greater crosspeak intensities. The lack of antiphase structure also means spectra... 

The first attempt to rationalize the spectra was in terms of information that they might provide concerning a more complex structure for the unit cell of cellulose I, perhaps along the lines suggested by Honjo and Watanabe in the 1950s. However, it soon became obvious that such a rationalization was not possible because the relative intensities within the multiplets were neither constant nor were they in ratios of small whole numbers as would be the case if the same unit cell prevailed throughout the crystalline domains. The conclusion was that the multiplicities were evidence of site heterogeniety within the crystalline domains, and that therefore native celluloses must be composites of more than one crystalline form. 

A survey of the vast material of catalytic chemistry shows that the structure of index groups is subject to certain regularities it may be compared to the structure of complex compounds which, according to Werner s theory, are subject to certain rules (6). It should be noted that most often such kinds of reactions are found to occur in the course of which two bonds of the initial molecules are broken (I.la) and two new bonds are formed in the products (I.lb). The transition from a to b is accomplished through the state of the multiplet complex (M). 

Fig. 3. The structure of the multiplet complex in subsequent layers. (Explanations in the text.)...

Compound A, CgHjo, yields three substitution products, C H9Br, on reaction with Bt 2- Propose two possible structures for A. The 1H NMR spectrum of A shows a complex four-proton multiplet at 7.0 8 and a six-proton singlet at 2.30 8. What is the structure of A ... 

These new derivatives were isolated in good yields (60-94%) as high boiling liquids and were fully characterized by NMR spectroscopy (1H, 13C, and 11B) and elemental analysis. The proton NMR of the starting material 1 shows a well-resolved multiplet and quintet for the trimethylene bridge. Upon monosubstitution, however, three complex multiplets are observed, indicative of the unsymmetrical structures of these derivatives. Also, the nonequivalence of the N-C carbon atoms is clearly apparent in the 13C NMR spectra of 2-4. 

As was mentioned in Section 6.2.3, phenomenological CF models have been extensively used in the past to rationalize the electronic structure of lanthanide complexes [4, 40-50], and they are still in use nowadays [38, 39, 78, 79]. The ab initio approach described above is, in principle, able to provide accurate energies and wave functions of multiplets in lanthanide complexes. Nevertheless, even if ab initio calculations appear to be successful, CF description is still of great... 

The RQDO /-values conform with the recommended values by Wiese et al. [18] for the 3p ( P) 4s-3p ( P) 4p transitions in C//better than those of the much more complex theoretical procedure of Ojha and Hibbert [17], who used large multiconfiguration expansions in the atomic structure code CIVS. On the other hand, the discrepancies between the length and velocity CIVS oscillator strengths are not negligible. Wiese et al. [18] remark that, for the case of the 4s " P-4p multiplet, the stronger lines measured by Bengtson et al. [16] seem to be affected by self-absorption (Table 2). 

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