Bridge proton exchange in B6H10 and 2-CH3B6H9; low temperature nuclear magnetic resonance spectra of static structures

1972 ◽  
pp. 1128 ◽  
Author(s):  
Vincent T. Brice ◽  
Howard D. Johnson ◽  
Sheldon G. Shore
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Low Temperature ◽  
Proton Exchange ◽  
Nuclear Magnetic Resonance Spectra ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

NUCLEAR MAGNETIC RESONANCE SPECTRA OF SIX-MEMBERED ALCYCLIC RING COMPOUNDS AT LOW TEMPERATURE: IV. PARTIALLY DEUTERATED 1,2-trans-CHLOROIODOCYCLOHEXANE

1962 ◽  
Vol 40 (9) ◽  
pp. 1870-1874 ◽  
Author(s):  
E. Premuzic ◽  
L. W. Reeves
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Low Temperature ◽  
Proton Resonance ◽  
Resonance Signal ◽  
Ring Compounds ◽  
Nuclear Magnetic Resonance Spectra ◽  
Signal Intensities ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

A 50/50 mole% mixture of 1-iodo-2-chloro-1,3,3-trideutero-, and 1-chloro-2-iodo-1,3,3-trideutero-cyclohexane has been synthesized. At −93 °C in a CS2 solution iodochlorocyclohexane shows resolution into diaxial and diequatorial halogen forms. Analysis of the adjacent proton resonance signal intensities shows that this compound exists 68±3 mole% in the diaxial halogan form. This is quite similar to 1,2-dibromocyclohexane, which has 70 mole% in the diaxial form, and is in contrast to 1,2-dichlorocyclohexane, which has a more stable diequatorial form.

Selenium-77 nuclear magnetic resonance studies of selenols, diselenides, and selenenyl sulfides

1988 ◽  
Vol 66 (1) ◽  
pp. 54-60 ◽  
Author(s):  
Khoon-Sin Tan ◽  
Alan P. Arnold ◽  
Dallas L. Rabenstein
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shift ◽  
Chemical Shifts ◽  
Proton Exchange ◽  
Exchange Reactions ◽  
Nuclear Magnetic Resonance Spectra ◽  
Ph Range ◽  
Magnetic Resonance Spectra ◽  
Nuclear Magnetic

77Se and 1H nuclear magnetic resonance spectra have been measured for selenols (RSeH), diselenides (RSeSeR), and selenenyl sulfides (RSeSR′), including selenenyl sulfides formed by reaction of glutathione and penicillamine with selenocystine and related diselenides. Exchange processes strongly affect the 77Se and 1H nuclear magnetic resonance spectra of all three classes of compounds. Sharp, exchange-averaged resonances are observed in the 1H nuclear magnetic resonance spectra of selenols; however, selenol proton exchange causes the 77Se resonances to be extremely broad over the pH range where the selenol group is titrated. Selenol/diselenide exchange [Formula: see text] also results in exchange-averaged 1H resonances for solutions containing RSeH and RSeSeR; however, the 77Se resonances were too broad to detect. Exchange reactions have similar effects on nuclear magnetic resonance spectra of solutions containing selenols and selenenyl sulfides. The results indicate selenol/diselenide exchange is much faster than thiol/disulfide exchange. The 77Se chemical shift depends on the chemical state of the selenium, e.g., titration of the selenol group of selenocysteamine causes the 77Se resonance to be shielded by 164 ppm, oxidation of the selenol to form the diselenide selenocystamine causes a deshielding of 333 ppm, and oxidation to form the selenenyl sulfide [Formula: see text] results in a deshielding of 404 ppm. 77Se chemical shifts were found to be in the range −240 to −270 ppm (relative to (CH3)2Se) for selenolates, approximately −80 ppm for selenols, 230–360 ppm for diselenides, and 250–340 ppm for selenenyl sulfides. The 77Se chemical shift is also affected by titration of neighboring carboxylic acid and ammonium groups, and their pkA values can be calculated from 77Se chemical shift data.

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