ID INADEQUATE spectra

The chemical shifts and the 29Si-29Si coupling constants (determined from the ID-INADEQUATE spectra) are summarized in Table 1. Figure 1 shows the ID-INADEQUATE spectrum of 4. If all the 29Si-29Si couplings can be determined, the structure of the compound can be easily derived. 

Crowded ID INADEQUATE spectra can be simplified by utilizing the editing properties of INEPT or DEPT249 in their combination with the INADEQUATE or by application of spectral editing as described for the 13C—13C SEMINA pulse sequence (,S MUT editing of IN AI )EQU ATE)249,250 or an INADEQUATE-SEFT combination251. 

FIGURE 28. 29Si—29Si INADEQUATE spectra of [Me3Si)2SiMeSiMe2]3SiMe. Top ID spectmm (r = 4.1 ms, A = 3 ps) bottom 2D spectrum (t = 4.1 ms). Reprinted from Reference 223. Copyright 1998, with permission from Elsevier Science... 

FIGURE 30. 29Si—29Si ID INEPT-INADEQUATE spectra top spectrum for 17, J = 108 Hz bottom spectrum for 18, J = 1.2 Hz (no experimental details given). Reproduced by permission of Wiley-VCH from Reference 238... 

Most of the carbon-carbon coupling constants published recently have been measured using 2D 13C-detected INADEQUATE spectra.39-44 ID INADEQUATE experiments were used less frequently43 45 due to potential overlap problems. The measured coupling constants are usually used to resolve stereochemical problems and also compared with theoretical values. 

Figure 28 ID INADEQUATE 77Se spectrum of [Re5OsSe8(CN)6]3 with a 4.1-ms fixed evolution period. Expanded spectra contain multiplets centred at —188.6 and —284.0 ppm. From Ref. 87, reproduced by permission of the American Chemical Society.

Figure5.75. The ID INADEQUATE experiment (b) selects for the carbon-13 satellites in the conventional carbon-13 spectra (a) and provides a means of measuring carbon-carbon coupling constants. Some residual parent resonances from lone C centres remain in (b).

Figure 4. ID Selective INADEQUATE spectra obtained by selective irradiation at 27.89 ppm, overlapped to spectra of a syndiotactic polypropylene sample.

In order to provide additional evidence for the above resonance assignments, the authors obtained double quantum and relay 2D-NMR spectra. The former experiment is better known as the ID-INADEQUATE experiment commonly performed on When executed on H, the appearance of the spectmm is identical to the INADEQUATE experiment, but does not suffer from poor sensitivity due to the low abundance of two adjoining NMR-active isotopes as it does in the more common... 

Fig. 5a. Part of the spectra obtained with the ID multiple selective INADEQUATE experiment III applied to cembrene 3 dissolved in CDCI3. The spectra were obtained after appropriate processing, showing the responses in the olefinic and the aliphatic regions after selective inversion of carbons...

Figure 5 Natural-abundance ID 13C INADEQUATE CR spectra of camphor at 500 MHz (A) and (B) left and right line of uncompensated INADEQUATE CR, respectively. (C) and (D) left and right line of off-resonance compensated INADEQUATE CR, respectively. (E) a one-scan single-pulse ID 13C spectrum for comparison. From Ref. 15, reproduced by permission of John Wiley and Sons.

Today, a number of one- and two-dimensional NMR experiments are available for the detection of homonuclear Li, Li and Li, Li couplings. Aside from the COSY experiment, the double quantum filtered COSY (COSY-DQF), the TOCSY, and the ID and 2D INADEQUATE experiments [24] have been successfully employed. An attractive feature of all these experiments is their sensitivity for small scalar interactions which give rise to crosspeaks even if line splittings in the corresponding ID spectra are not resolved. This was first demonstrated with COSY experiments for a paramagnetic nickel complex [82] and for quadrupolar nuclei in the case of boron-11 [83]. 

The rearrangement of the cage hydrocarbon diazo-nium ion [1] in the presence of water could lead to three possible alcohol products [2], [3] and [4]. Only two alcohol products were obtained from this reaction in isolated yields of 38% and 7%. The structures of these two products could only be determined by the 2D INADEQUATE experiment due to the hydrocarbon nature of their structures, and therefore, the lack of any distinguishing details in the proton spectra. Each compound also had the same number of methylene, methine and quaternary carbons, thus precluding the utilization of structure determination by simple ID spectroscopy. 

The multi-receiver PANACEA experiment is designed aroxmd the INADEQUATE pulse sequence [32, 33] and also incorporates ID spectra, multiplicity edited 2D HSQC-s and 3D J-HMBC experiments. In addition, PANACEA does not require the conventional field/frequency lock and can be recorded in pure liquids. 

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