Nitrogen electronic spectra

When the lone electron pair is protonated, the nitrogen chemical shift moves by ca. 100 p.p.m, to higher field. Large upheld shifts are also found when a compound exists in a tautomeric form with a proton on the nitrogen. The nitrogen NMR spectrum is often of considerable value in studies of tautomerism of this type. 

Acetylpyridine thiosemicarbazone forms [Co(8)2Cl2], which is isolated from hot ethanol [178], Based on infrared spectra the pyridyl nitrogen is coordinated and bonding is NS with two chlorines bringing the coordination number to six. The complex is a non-electrolyte in DMF, has a magnetic moment of 4.13 B.M., and the electronic spectrum has bands at about 8160 and 17 860 cm consistent with octahedral stereochemistry. 

Thus, the historical development of the chemistry of metallocorrolates until 1980 includes complexes with Cu2+, Ni2+, Pd2+, Fe3+, Co3+, Rh+, Mo5+ and Cr5+. The palladium complex has been isolated as its pyridinium salt since the neutral species was too unstable to be isolated or spectroscopically characterized [19]. The nickel complex was non-aromatic, with one of the potentially tautomeric hydrogens displaced from nitrogen to carbon in such a way as to interrupt the chromophore. In contrast the electronic spectrum of the paramagnetic copper complex is similar to those of the fully conjugated lV(21)-methyl derivatives [11],... 

Figure 6. Sulfur 2p electron spectrum from wool yarn exposed to oxygen plasma (top) and to a nitrogen plasma (bottom).

Figure 9.6 Electronic spectrum of nitrogen dioxide and ranges of its different photochemical behaviour quantum yield of N02 photodissociation between 300 and 420nm [61...

The association constant of pyridazine with ethanol was found to be 4.9 (from electronic absorption spectra) and 6.8 (infrared absorption spectra), and the corresponding values for the strength of the hydrogen bond are 4.2 and 4.6 kcal. The hydrogen-bonded form of P3n-idazine was considered to comprise one alcohol at one azine-nitrogen at small mole ratios of alcohol to azine and to involve the second nitrogen at high mole ratios (an additional shift in the electronic spectrum. The association constants (3.1-3.8) of pyridine, quinoline, and isoquinoline with methanol in carbon tetrachloride have been determined by infrared spectroscopy. 

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