✍ Scribed by M. Avignon; P. V. Huong; J. Lascombe; M. Marraud; J. Neel
No coin nor oath required. For personal study only.
Some experimental data are given on the infrared spectra between 3300 and 3500 cm-* of dilute solutions in carbon tetrachloride of three t,ypes of model compounds: CH,-CONH-CH(ltl)-COKH(Itz), (I); CH,-COS (CH,)-CH (11 J-COKH(R,), (11) and CHa-CONH-CH(Rl)-CON(R,), (111). In studying the S -H stretching bands, it was found that there are two types of intramolecular hydrogen bonds in these mo!ecules; these result in two different cyclixed conformations, C S and C,, which conta'n, respectively, five and seven atoms in the ring. By using model substances I, 11, and 111, in which the nitrogen atoms are unequally substituted, it is possible to identify the K-H stretch:ng bands which are to be ascribed to the N-H oscillators included in the two d:fferent chelated conformations. It is found a!so that the stretching frequency of a free S -H oscillator depends upon the substltuerit on the nitrogen atom. Thus, it is poss.ble to observe, with some of the model compounds I, four d fferent absorption bands 1ocat.ed at 3340, 3420, 3440, and 3460 cn-1. The first two are ascribed to the N-H oscillators included in the H-bonds which lO(;li the C, and C5 conformations; the last two rorrespond to free K-H which differ with the substituent on the nitrogen atom.
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