wizyta

od 2020-09-20

Title: Proton and fluorine nuclear magnetic resonance studies of molecular motion in dimethyl sulfoxide-boron trifluoride complex

Source: Journal of Magnetic Resonance (1969)

Year : 1983

Abstract:

Proton and fluorine second moments and spin-lattice relaxation times have been studied over a wide temperature range in solid dimethyl sulfoxide-boron trifluoride (CH3)2SO · BF3 and in its deuterated analog (CD3)2SO · BF3. The results indicate that the two methyl groups are dynamically inequivalent within the molecule and reorient at and above 77 K about their threefold symmetry axes (C3) with different frequencies and with activation energies of 6.69 and 10.45 kJ/mol. The BF3 group is rigid at 77 K, while above 135 K it reorients about its C3 symmetry axis with an activation energy of 15.93 kJ/mol. The low-temperature fluorine relaxation is controlled by the reorientation of the methyl groups which is faster than that of BF3. This allows one to deduce for the fluorine-proton second moment a value indicating that the BF3 group is closer to one of the two methyl groups in the proton-containing compound.

DOI: 10.1016/0022-2364(83)90273-1   (Pobrane:  aktualizowanie)