Determine the point group for EACH of the possible structural arrangements of (a) AsF $2 \mathrm{Cl} 3$, and (b) $\mathrm{AsF} 3 \mathrm{Cl} 2$.

Assuming a static structure, indicate the number and relative intensities of the signals that you would expect to see in the 19F NMR spectrum of each molecule. Hint: draw their VSEPR structures could be helpful.

Question

Determine the point group for EACH of the possible structural arrangements of (a) AsF $2 \mathrm{Cl} 3$, and (b) $\mathrm{AsF} 3 \mathrm{Cl} 2$.

Assuming a static structure, indicate the number and relative intensities of the signals that you would expect to see in the 19F NMR spectrum of each molecule. Hint: draw their VSEPR structures could be helpful.

Accepted Answer

∻Solution∻ ‖ 1 ⋮ **Determine the point group for AsF$_2$Cl$_3$**: To determine the point group, we must first predict the molecular geometry using VSEPR theory. AsF$_2$Cl$_3$ has five regions of electron density around the central As atom (two F atoms, three Cl atoms), which suggests a trigonal bipyramidal geometry. However, the actual geometry will depend on the arrangement of the F and Cl atoms. ‖ ‖ 2 ⋮ **Possible structures for AsF$_2$Cl$_3$**: There are two possible structures for AsF$_2$Cl$_3$: one with both F atoms in axial positions and another with one F atom in an axial position and the other in an equatorial position. The point group for the first structure is $C_{2v}$ (due to the presence of a C2 axis and two vertical mirror planes), and for the second structure, it is $C_s$ (due to the presence of a single mirror plane). ‖ ‖ 3 ⋮ **Determine the point group for AsF$_3$Cl$_2$**: AsF$_3$Cl$_2$ also has five regions of electron density, suggesting a trigonal bipyramidal geometry. The possible structures are with three F atoms in equatorial positions and two Cl atoms in axial positions, which gives a point group of $D_{3h}$ due to the presence of a C3 axis, horizontal mirror plane, and two C2 axes perpendicular to the C3 axis. ‖ ‖ 4 ⋮ **19F NMR spectrum for AsF$_2$Cl$_3$**: For the $C_{2v}$ structure, we would expect two signals of equal intensity due to the two equivalent F atoms. For the $C_s$ structure, we would expect two signals of different intensities due to the non-equivalent F atoms. ‖ ‖ 5 ⋮ **19F NMR spectrum for AsF$_3$Cl$_2$**: For the $D_{3h}$ structure, we would expect one signal since all three F atoms are equivalent. ‖ ∻1 Answer∻ ⚹ AsF$_2$Cl$_3$: Point group $C_{2v}$ or $C_s$, 19F NMR with two signals (equal or different intensities). AsF$_3$Cl$_2$: Point group $D_{3h}$, 19F NMR with one signal. ⚹ ∻Key Concept∻ ⚹ Point groups and 19F NMR spectra are determined by the symmetry and equivalence of fluorine atoms in a molecule. ⚹ ∻Explanation∻ ⚹ The point group is determined by the molecular geometry and symmetry elements present, while the 19F NMR spectrum depends on the equivalence or non-equivalence of the fluorine environments.◊What is the VSEPR structure of AsF3Cl2?⍭ Generate me a similar question◊⚹

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