The 2 H NMR experiments were performed on a Bruker 400 MHz spectrometer operating at a Larmor frequency of 61.405 MHz with either a 2.5 mm HX, a triple resonance low-temperature (LT) 3.2 mm probe or a triple resonance 4.0 mm probe. On the 2.5 mm probe the radio frequency (RF) amplitude of the pulses was 100 kHz, which was measured by the nutation behaviour of deuterated ethanol (C 2 H 5 OD). The 2 H shifts were referenced externally to C 2 H 5 OD at 2.50 ppm. For short high-power adiabatic pulses the tanh/tan 29 pulse scheme was employed with 5 MHz sweep width and a 50 µs pulse length.