Proton Magnetic Resonance of Solid 1,1,1,2-Tetrachloro-2-methylpropane

The molecular motion in the crystal lattice of 1, 1, 1, 2-tetrachloro-2-methylpropane was studied, by proton magnetic resonance absorption measurements, over the temperature range between 30°C and −190°C. The absorption-line witdhs changed at −62°C. The second moments remain almost constant, about 5 gauss2, between from −63°C to about −150°C, whereas above −62°C the values fall suddenly to 0.5 gauss2. From the analysis of the proton second moment, it was found that, in the high-temperature phase, the molecules rotate almost freely in the crystal lattice, while in the low-temperature phase, the major molecular motion is the rotation of the methyl groups about the C–CH3 bonds in the molecule.