Molecular Motions of [N(C₂H₅)₄]⁺and [N(CH₃)₄]⁺ions by¹H Nuclear Magnetic Resonance Relaxation in [N(C₂H₅)₄]₂CoCl₄and [N(CH₃)₄]₂CoCl₄Single Crystals

Abstract

The line widths and spin-lattice relaxation times of protons in [N(C 2 H 5) 4 ] 2 CoCl 4 and [N(CH 3) 4 ] 2 CoCl 4 single crystals were investigated in the temperature range 160-400 K. The temperature dependences of the spin-lattice relaxation times are attributed to the molecular motions of the ethyl and methyl groups in the [N(C 2 H 5) 4 ] + and [N(CH 3) 4 ] + ions respectively. The NMR line widths indicate that the ethyl groups in [N(C 2 H 5) 4 ] 2 CoCl 4 have one more degree of freedom than the methyl groups in [N(CH 3) 4 ] 2 CoCl 4. The experimental results are interpreted in terms of the reorientations of the methyl and ethyl groups.