Theoretical Anisotropic Hyperfine Tensors in Neutral Radicals

Abstract

Anisotropic hyperfine tensors were calculated for C—H, (C—CH3), allyl, and perinaphthenyl. In the McConnell and Strathdee theory, the anisotropic proton tensor depends primarily on the STO exponent chosen for the 2pπ, carbon atom orbital. By decreasing the exponent ζπ from the normal Slater value to ~ 1.3, the effect of σ-spin density in the C—H bond could be taken into account. However, this reduction in ζπ yields too small a value for [Formula: see text] which governs the anisotropic 13C tensor. Contributions to the anisotropic proton and 13C hyperfine tensors are discussed, and the results compared with recent abinitio calculations, as well as single-crystal and liquid crystal data.