VSEPR theory suggests that the sulfur pentafluoride ion SF₅⁻adopts a trigonal bipyramidal structure. Predict the coupling pattern expected for the ¹⁹F-NMR spectrum of SF₅⁻obtained at very low temperatures.

Question

Quizplus · Accepted Answer

The trigonal bipyramidal structure of SF₅⁻ has two types of fluorine atoms, axial and equatorial. In NMR spectroscopy, the splitting of the signal from the equivalent nuclei is given by the n+1 rule (where n is the number of neighboring nuclei). The axial fluorines have only three equivalent fluorines as neighbors, while the equatorial fluorines have four. Therefore, the axial fluorines will give a triplet while the equatorial fluorines will give a quartet. Hence, the ¹⁹F-NMR spectrum of SF₅⁻ obtained at very low temperatures will have two groups of resonances, one appearing as a triplet and the second as a quartet.

VSEPR Theory Suggests That the Sulfur Pentafluoride Ion SF5− adopts

VSEPR Theory Suggests That the Sulfur Pentafluoride Ion SF₅⁻adopts