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The r α ‐structures of partially oriented 1,2,4,5‐and 1,2,3,4‐tetrachlorobenzene determined from their proton magnetic resonance spectra with natural abundance 13 C‐satellites
Author(s) -
Diehl P.,
Dombi G.,
Boesiger H.
Publication year - 1980
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270140412
Subject(s) - chemistry , liquid crystal , spectral line , isotropy , molecule , proton , chemical shift , hydrogen bond , carbon fibers , bond length , abundance (ecology) , coupling constant , materials science , physics , condensed matter physics , organic chemistry , optics , composite number , composite material , particle physics , fishery , biology , quantum mechanics , astronomy
By recording two spectra of the same molecule in different nematic liquid crystals, and analysing the data simultaneously, information has been obtained on the molecular structures of 1,2,4,5‐ (1) and 1,2,3,4‐tetrachlorobenzene (2). Carbon–hydrogen and carbon–carbon internuclear distance ratios, as well as bond lengths and bond angles, were computed and corrected for harmonic vibrations. Only part of the molecular structure of 2 could be derived with reasonable precision; the reasons for this limitation are discussed. The spectra of the two isomers were also analysed in isotropic solvents in order to determine the indirect coupling constants. One‐ and two‐bond 13 C isotope effects on the chemical shifts of the protons were observed. The solvent effects of the different nematic liquid crystals on the structure were found to be small compared with the experimental error.