NQR in tert-butyl chloride

Tert-butyl chloride has been broadly studied experimentally through various techniques such as X-ray crystallography, DTA, and NMR. It was also studied experimentally through nuclear quadrupole resonance (NQR), but this study was limited and incomplete. In this paper, we present a more detailed study of TBC through the NQR of ³⁵Cl. Our results show that near 120 K, the onset of the CH₃ groups semirotations around symmetry axis C₃ takes place with an activation energy U=16.1 kJ mol⁻¹. This intramolecular movement produces a T₁ minimum near 148 K and is the dominant mechanism of the nuclear spin-lattice relaxation in phase III of this compound. In phase II of TBC, we show that there are not only methyl groups semirotations, but also semirotations of the whole molecule around a different axis from the symmetry axis C′₃ (C–Cl bond) with an activation energy of E=10.4 kJ mol⁻¹.