Broad signals

The first fraction (bp 30-40 C) contains decenes which are formed by palladium-catalyzed isomerization of l-decene (indicated by a broad signal at 6 5.2-5.5 in the H NMR spectrum). 

The CH connectivities can be read off from the CH COSY plot thus the complete pattern B of all //atoms of the molecule is established. At the same time an O//group can be identified by the fact that there is no correlation for the broad signal at <5// = 4.45 in the CH COSY plot. 

Tile low-temperature ESR spectrum of the anion radical of purine disclosed that about 45% of the spin density is localized at position 6 (80BCJ1252), although a single very broad signal for N(7) and N(9) did not allow discussion of the tautomerism. 

Quantitative accuracy and precision (see Section 2.5 below) often depend upon the selectivity of the detector because of the presence of background and/or co-eluted materials. The most widely used detector for HPLC, the UV detector, does not have such selectivity as it normally gives rise to relatively broad signals, and if more than one component is present, these overlap and deconvolution is difficult. The related technique of fluorescence has more selectivity, since both absorption and emission wavelengths are utilized, but is only applicable to a limited number of analytes, even when derivatization procedures are used. 

The great advantage of the mass spectrometer is its abihty to use mass, more accurately the mass-to-charge ratio, as a discriminating feature. In contrast to, for example, the UV detector, which gives rise to broad signals with little selectivity, the ions in the mass spectrum of a particular analyte are often characteristic of that analyte. Under these conditions, discrete signals, which may be measured accurately and precisely, may be obtained from each analyte when they are only partially resolved or even completely umesolved from the other compounds present. 

To gain insight into the polymer structure, C NMR spectroscopy was performed. From examination of the broad signals in Figure 1 it can be seen that this experimental approach yields little information. There is little additional information obtained from examination of the broad signals in a ySi NMR spectrum (Figure 2) of this polymer, except for the observation of residual Me,SiCl by-product at ca. 

The H-NMR spectrum of 2 in CDCI3 (Figure 1) exhibits broad unresolved resonances in the aromatic region similar to those found in the monomer. Broad signals with lack of resolution are consistent with magnetic non-equivalence of the methyl group protons resulting from a mixture of triad tacticities. 

While mononuclear octahedral Ni11 complexes often show relatively broad signals, nuclear relaxation enhancement and sharp signals may be observed in related dimer species 350,351 This has been taken advantage of for a detailed NMR investigation of a series of weakly ferromagnetically spin-coupled dinuclear octahedral Ni11 centers.352... 

No solid state NMR experiment is able to obtain spectra comparable to those routinely recorded in the liquid state. Thus multiplets become broad singlets and, if close together, overlap to give a broad signal envelope . While the differentiation of aromatic and aliphatic protons is simple, the information available is, from the point of view of structure determination, very limited. Thus we shall not provide an example. 

The nB NMR spectrum of the product showed two broad signals at 27.7 ppm and 24.7 ppm, which are attributed to boron atoms of the borazine ring and the boryl substituents, respectively. These results are consistent with the formation of the /i-tri [bis( methy lam ino (boryl (methyl jam ino]borazine 13 as the main product (Fig. 6). No free B(NHCH3)3 was detected. 

Alkyl-CON H2/-CON H R 9-7 Often broad but frequently couple. Primary amides often appear as two broad signals due to partial double bond character of amide bond. Often slow to exchange and may require warming/mild base... 

Spectrum 6.8 4-Bromobenzamide showing typical appearance of primary amide protons as two non-equivalent broad signals separated by about 0.6 ppm. 

Let s return to our amides. In primary amides, where R and R" are both just protons, we can expect to see them as two, distinct, broad signals (Spectrum 6.8). 

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