Group 2 elements amides

Humin isolates from sediments of the Mew York Bight and Potomac River estuary have spectra that are notably different in that aromatic carbons are the dominant components. The spectra resemble that of humin isolated in the same manner from an aerobic soil from southern Georgia (Figure 5). However, unlike the humin from soil which shows a significant peak for carboxyl carbon (175 ppm), spectra of humin from the New York Bight and the Potomac River do not display a discreet peak at 175 ppm and appear to be depleted of carboxy 1/amide groups. Elemental data for these humins (19) are consistent with the NMR results. Atomic H/C ratios of less than 0.8 are not typical of humic material but more like those of highly aromatic coal or coal-like products. The NMR spectra also resemble... 

Low-coordinate species of the main group elements of the second row such as carbenes, olefins, carbonyl compounds (ketones, aldehydes, esters, amides, etc.), aromatic compounds, and azo compounds play very important roles in organic chemistry. Although extensive studies have been devoted to these species not only from the physical organic point of view but also from the standpoints of synthetic chemistry and materials science, the heavier element homologues of these low-coordinate species have been postulated in many reactions only as reactive intermediates, and their chemistry has been undeveloped most probably due to... 

Once the normal modes are computed, the nature or properties of the excited vibrational states can also be of use for structural studies. The most obvious of these is the dipole strength, directly proportional to the IR absorption intensity, which will depend on the environment and stereochemistry of the amide group. A key element in utilizing these calculational results is the use of intensities, through spectral simulation, to compare pre-... 

Imides are usually included for main group elements because bi- and oligonuclear metal imides are ubiquitous and were often developed in parallel with the amides. They generally feature trivalent nitrogen, as in [ As(Cl)(p-NBu )]2. Imido derivatives of the transition... 

Main-chain carbonyl and amide groups are most often hydrogen bonded to each other, generally in elements of secondary structure. 

---