Rotational Isomerism in Hydrazine

Abstract

LETTERS TO THE EDITORAs is usual in this type of calculation 6 we suppose these differences of the localization energies to be equal to the differences of the activation energies. As the activation entropies are constant to a good approximation,6 we may calculate the percentage of meta isomer in the reaction product from the values of e. and a.k, which in turn are obtained from the data on bond distances and dipole moments from the literature. Some of the results of our calculations are shown in Table 1.The agreement between our results and the experimental values is surprisingly good for the first group of substituents. For the second group all theoretical values are higher than the experimental results, which is ascribed to the hyperconjugation of the -CH3 and -CH2X group with the pentadienate cation, which tends to lower the energy of the transition state for ortho and para substitution. This effect of hyperconjugation was not taken into account in the present calculations. 1 M. J. S. Dewar, The Electronic Theory of Organic Chemistry (The Clarendon Press, Oxford, 1949). 2 We use the same convention of sign as Dewar (I.e.) '

Crystallography

“…a trans(C2h)-configuration has also been suggested, on the basis of infra-red and Raman spectra, for the solid at -190°. 155 It is likely that there is only a small difference in stability between the various forms The p-uranium structure has been s01ved.l~~ and that the eclipsed molecules are stabilised in the crystal by hydrogen bonds.…”

Infrared Spectroscopy

“…The molecular studies on specific molecules include: acetylpropyl alcohols (231), metal acetyl acetonates (108), acetylene and substituted acetylenes (06, 170, 172, 319), aliene (284), ammonia and deuteroammonia (312,415), arsine (269), benzene (181), fluorinated benzenes (100, 273), boron compounds (229,306,333,363), substituted butanes (331), trichlorobutene (164), 2-methylbutane ( 46), carbon monoxide (405), chlorine monofluoride (268), chlorine oxides (113, 167), cyanogen and cyanogen chloride (275), cyclohexane (218,219), cyclo-octatetraene (227), cyclopentanes (253), cycloparaffins. (239), diazomethane (80), dibromoethane (263), ethylene (300,319,370), substituted ethylenes (75,217,384,385), ethyleneimine (114,177,379), ethylene oxide (153, 378), ethylene sulfide (379), formaldehyde (220), difluoroformaldehyde (266), fluorine monoxide (192,267), formic acid and formate ion (375), germanium tetrafluoride (60), hydrazine (402), substituted hydrazines (14, 15, 17) deuterated hydrogen cyanide (314), hydrogen fluoride (342), hydrogen peroxide (138), hydrogen sulfide (4,174, 228, 276), hydroxyl (179), hypochlorous acid (168), perfluoroalkyl iodides (165), isocyanic acid (173, 313), mesitylene complexes (291), metallic dimethyls (43,44), halógena ted methanes…”