Aniline protons, relative shifts

This static model for second sphere complex formation is not fully valid and the above values of AH do not have full thermodynamic significance. Thus, if one assumes a static model for the second sphere complex. Equation I enables the relative shifts of the ortho, meta, para, and NH2 protons to be calculated for any position of the aniline. Such calculations give qualitative but not quantitative agreement with experiment. The nature of the disagreement is illustrated by the data in Table I. 

Table I. Calculated Relative Shifts of Aniline Protons...

Ultraviolet. Benzene has a series of relatively low intensity absorption bands in the region of 230 to 270 nm. When there is a substituent on the ring with nonbonding electrons, such as an amino group, there is a pronounced increase in the intensity of these bands and a shift to longer wavelength. Aniline shows an absorption band at 230 nm (e = 8600) and a secondary band at 280 nm (e = 1430). Protonation of the amino groups reduces these effects and the spectmm resembles that of the unsubstituted benzene. 

It is noted that the magnitude of the contact contribution varies considerably between the and resonances. In order to obtain structural information on the lanthanide complexes at least six Gj values are, in general, required (three polar coordinates to fix the position of the lanthanide ion relative to the molecule, two additional angles to define the main magnetic axis orientation, and one signed value for the proportionality constant). The six nuclei used to provide these Gj values need not necessarily be protons. In a later paper Reilley et al. (388) discuss certain refinements of their method and apply it to a wide variety of LSR complexes including those of water, pyridines, alcohols, anilines, aliphatic amines, and ketones. The contact contributions of the C shifts of Ln(DPA)3 and Ln(MDPA)3 complexes are found to be important even for carbons five bonds removed from the lanthanide ion. (390)... 

As a substituent on an aromatic ring, the amine salt group has an unusually uniform effect on the chemical shifts of the ortho, meta and para hydrogens. The series of aniline salts presented indicate the minimal effect that the type of acid involved, the solvent employed and the degree of amine substitution have on the chemical shift of the phenyl protons. The aromatic resonance for all of these aniline salts appears as a relatively sharp peak in the narrow chemical shift range from 7.50-7.55 ppm. 

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