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Structural studies of halogen adducts of diorganyl chalcogenides in solutions by 1 H, 13 C, 77 Se and 125 Te NMR
Author(s) -
Nakanishi Warō,
Hayashi Satoko,
Tukada Hideyuki,
Iwamura Hiizu
Publication year - 1990
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610030603
Subject(s) - chemistry , bromine , adduct , chemical shift , halogen , selenide , nmr spectra database , iodine , trigonal bipyramidal molecular geometry , tellurium , molecule , medicinal chemistry , selenium , inorganic chemistry , spectral line , organic chemistry , alkyl , physics , astronomy
1 H, 13 C, 77 Se and 125 Te NMR spectra were measured for several sulphides, selenides, tellurides and their halogen adducts to establish the criteria for distinguishing trigonal bipyramidal (TB) adducts from molecular complexes (MCs). TB formation caused large downfield shifts for methyl protons and methyl, ipso and para carbons of methyl and phenyl selenides and tellurides. Large downfield shifts (> 100 ppm) were also observed for selenium and tellurium by the formation of TB from the parent selenides or tellurides. The plots of the 125 Te vs 77 Se chemical shifts for a set of corresponding compounds gave a straight line with a slope of 1·74, showing that the linear relationship holds well for tellurides and selenides and their TB adducts examined in this work. Upfield shifts of the ipso carbons were characteristic of MC formation. The para carbon signals of MC appeared downfield relative to those of the parent selenides, although the shift values were not so large. The 77 Se signals for MC shifted slightly downfield (⩽ 10 ppm). The dissociation constants for iodine adducts of dimethyl selenide and selenoanisole were determined. The MC structure of bromine adducts of sulphides is well demonstrated on the basis of the criteria set out. 1 H and 13 C NMR spectra of ethylbenzene and ethers were also recorded in the presence of iodine or bromine. However, their chemical shifts were the same as those in the absence of iodine or bromine, within experimental errors.