Proton, deuterium, and chlorine-35 nuclear magnetic resonance of solid and liquid t -butyl chloride

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Abstract
Proton spin‐lattice (T1) and rotating frame (T1ρ) relaxations have been measured in (CH3)3CCl from 90°K to the melting point (249°K). In Solid III (below 183°K) there is a minimum in T1 which is due to rotation of the methyl groups about an axis perpendicular to the plane containing the three protons. In this phase T1ρ exhibits an inflection which is assigned to a motion of the molecule about the C–Cl bond direction. In Solid II (from 183 to 223°K) T1 has a minimum due to the motion around the C–Cl bond direction. In the fcc Solid I the molecules are tumbling isotropically and translational diffusion is relatively fast. Chlorine‐35 nuclear quadrupole resonance (NQR) is observed in Solids III and II. The observed NQR frequency depends on temperature as predicted by the Baver theory except in the immediate vicinity of the phase transitions where the apparent torsional frequencies decrease significantly. Coefficients of self‐diffusion (D) were measured in the liquid from the melting point to the gas‐liquid critical point (490°K). D is represented by D = (12.8 ± 0.7)10−3 exp[−(3.69 ± 0.03)/RT] to within 40° of the critical point whereupon D gradually begins to increase very rapidly with further increase in temperature to a value of 1.2 × 10−3 cm2 sec−1 in the gas. Rotational correlation times τ2 have been measured for deuterium, protons, and chlorine‐35 in the liquid from 223 to 300°K. Values of τ2 for D, H, and Cl are unchanged at the freezing transition between the liquid and Solid I, but are discontinuous at the Solid I and Solid II transition. Rotational correlation times for molecular tumbling and methyl group rotation are calculated from the values of τ2 for H, D, and Cl.