Nuclear Spin—Spin Coupling Involving Heavy Nuclei. The Coupling of Tl205 and Tl203 with H1 Nuclei in (CH3)2TlX and (CH3CH2)2TlX Compounds

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Abstract
The nature of the spin‐coupling interaction between thallium nuclei and protons in (CH3)2TlX and (CH3CH2)2TlX compounds has been examined. In aqueous solution where the corresponding cations R2Tl+ are present, the coupling constants are characteristic of the alkyl group attached to thallium. In pyridine solution the coupling constants are dependent upon the nature of X and are larger than those in the parent cation. Using a simplified model for contact interaction employing optical hyperfine splitting constants, an estimate of the contact contribution to the total thallium—proton coupling constant has been made for the series R3Tl, R2Tl+, and RTl++. It is found that irrespective of the nature of R the observed proton—thallium coupling constants increase from left to right in the relative proportions predicted by the model. The results are consistent with the conclusion that the thallium and hydrogen nuclei are coupled mainly through the Fermi contact interaction.