INADEQUATE spectroscopy

Through-bond and through-space solid-state NMR correlation experiments including CP-INADEQUATE at natural isotope abundance have been applied by Brus and Jegorov to establish the structure and dynamic behaviour of simvastatin (C25H38O5), an active metabolite which inhibits 3-hydroxy-3-methyl-glutaryl coenzyme A, (HMG-CoA) reductase, the enzyme that is necessary in an early step of the cholesterol synthesis. 2D INADEQUATE spectroscopy has been applied by Meier et to establish the structures of a series of fullerene derivatives. 

D-INADEQUATE spectroscopy can conveniently disclose the connectivity of each carbon atom embedded in a molecule and has found widespread use in structural elucidation of organic compounds. This technique is extremely powerful when the size of one-bond coupling (V) is much larger than that of long-range couplings... 

TACTICITY Various 2D-NMR methods including H J-resolved spectroscopy, H- H COSY spectroscopy, C- H COSY spectroscopy and INADEQUATE spectroscopy have been... 

High-pass filter A filter used to select a coherence order > p. INADEQUATE Correlation spectroscopy in which the directly bonded C nuclei are identified. 

Summary Many cyclic and linear transition metal-silicon compounds have been obtained by the elimination of alkali halides. The structures of these complexes were determined by INEPT and INEPT-INADEQUATE NMR spectroscopy. 

Temperature programmed sulfidation or temperature programmed reaction spectroscopy usually deal with more than one reactant or product gas. In these cases a TCD detector is inadequate and one needs a mass spectrometer for the detection of all reaction products. With such equipment one obtains a much more complete picture of the reaction process, because one measures simultaneously the consumption of reactants and the formation of products. 

The coupling of Naphtol AS or its phenyl-substituted derivatives with diazonium salts from variously substituted anilines in aqueous alkaline solution (section 4-11) gave incomplete reactions and impure products in some instances, probably because these coupling components have inadequate solubility in aqueous media. Pure dyes in ca. 90% yields were obtained by reaction in dimethylformamide in the presence of sodium acetate. Metallisation of these o,o -dihydroxyazo ligands with sodium chromium salicylate or a cobalt(II) salt gave metal-complex dyes in 80-100% yields [22]. Specific structural isomers of these complexes were identified by i.r., n.m.r., Raman and UV/visible spectroscopy [23]. 

In order to assign the chemical shifts of the carbon atoms of the conjugated diene system of each CLA isomer, it was necessary to conduct INADEQUATE, HMBC (heteronuclear multiple bond correlation) and two-dimensional 1H-13C correlation spectroscopy (COSY) techniques on the carbon signals of the diene system of the ,Z-isomers. The results of these experiments for the CLA isomers are summarized in Table 13. 

Currently, there are no accurate methods available for quantifying the aliphatic bridges in the coal macromolecule. Quantitative nature of the application of infrared (IR) spectroscopy is limited to certain general types of functional groups or bond types. Nuclear magnetic resonance spectroscopy, despite the success of dipolar dephasing techniques to decipher the extent of substitution on carbon atoms, is still inadequate to distinguish distinct structural entities . 

There are a large number of structural parameters for NMR of different nuclei and many examples of how they can be applied to the analysis of hydroxylamines, oximes and hydroxamic acids. Fortunately though, there are many very clear, meticulously written descriptions of INEPT, DEPT, INADEQUATE, COSY, NOESY and the like, in one- and two-dimensional NMR spectroscopy, that are cited in the references. Since their content is beyond the scope of the present chapter, a brief mention of some of the fundamental concepts that are essential for its understanding by the nonspecialist is in order. 

On the other hand, the digermirane (18) reacts with Cgo to afford the 1,4-adduct (19, twist form) selectively15. The structure of the 1,4-adduct was confirmed by 13C-13C INADEQUATE (Incredible Natural Abundance Double Quantum Experiment) spectroscopy (equation 5). The rate of disappearance of Cgo was suppressed by addition of diazabicyclo[2.2.2]octane and 1,2,4,5-tetramethoxybenzene. Furthermore, the reaction was completely inhibited by addition of rubrene as triplet quencher. One plausible rationale for these observations is that an exciplex intermediate may be responsible for formation of the products (Scheme 6). 

Vibrationally resolved PES and matrix-isolation spectroscopy are classic tools for systems of a few atoms but fail for larger sizes, the former because of spectral congestion and the latter for inadequate signal intensity. 

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