Bonding information from fluorine NMR for alkoxy tungsten pentafluorides

The ¹⁹F chemical shifts have been measured for the fluorines bound to tungsten in the compounds ROWF₅ where R is CH₃, ClCH₂CH₂, Cl₂CHCH₂, Br₃CCH₂, Cl₃CCH₂, F₃CCH₂, F₂CH(CF₂)₃CH₂, F₃CCF₂CH₂, and (CF₃)₂CH. For the series as written, both the axial and equatorial fluorines resonate at progressively lower field, and the change in resonant position from one compound to another is twice as great for the axial as for the equatorial fluorines. These results are interpreted in terms of σ- and π-bonding contributions.