Unexpected temperature dependence of 1H paramagnetic shift in MAS NMR of nickelocene

This work revisits the temperature dependence of 1 H paramagnetic shift in nickelocene as a potential nuclear magnetic resonance (NMR) thermometer under fast magic angle spinning (MAS) rate. Surprisingly, an abnormal temperature dependence of 1 H paramagnetic shift has been observed. In addition to a 1/T dependence term, a 1/T2 dependence term must be included to correctly describe the curvature behavior of the d 1 H-T correlation under fast MAS rate. (c) 2024 The Authors. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co. Ltd. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/).