Thallium chemical shift referencing

Thallium chemical shifts are very sensitive to chemical and physical conditions. This makes accurate chemical shift referencing difficult. Therefore, chemical shifts are usually referenced to the H-1 reference multiplied by a standard factor. However, past papers are referenced to TlNO3 solution in water at infinite dilution. The chemical shift of TlNO3 at infinite dilution is measured accurately and found to be -22.16 and 0.75 ppm for Tl-203 and Tl-205, respectively relative to the standard frequency ratios to proton. The behavior of thallium chemical-shift with concentration and temperature are determined and discussed in relation to the degree of ionic association. (C) 2021 Elsevier Inc. All rights reserved.