Problem 4
Give explanations for the following observations. (a) \(\mathrm{p} K_{\mathrm{a}}\) values for \(\mathrm{CF}_{3} \mathrm{CO}_{2} \mathrm{H}\) and \(\mathrm{CH}_{3} \mathrm{CO}_{2} \mathrm{H}\) are 0.23 and \(4.75,\) respectively. (b) The dipole moment of a gas phase \(\mathrm{NH}_{3}\) molecule is \(1.47 \mathrm{D},\) but that of \(\mathrm{NF}_{3}\) is \(0.24 \mathrm{D}\) (c) In electrophilic substitution reactions in monosubstituted aryl compounds \(\mathrm{C}_{6} \mathrm{H}_{4} \mathrm{X}, \mathrm{X}=\mathrm{Me}\) is activating and ortho- and para-directing, whereas \(\mathrm{X}=\mathrm{CF}_{3}\) is deactivating and meta-directing.
Problem 8
Discuss the role of halide acceptors in the formation of interhalogen cations and anions.
Problem 9
Predict the structures of (a) \(\left[\mathrm{ICl}_{4}\right]^{-},(\mathrm{b})\left[\mathrm{BrF}_{2}\right]^{+}\) (c) \(\left[\mathrm{ClF}_{4}\right]^{+}\) (d) \(\mathrm{IF}_{7}\) (e) \(\mathrm{I}_{2} \mathrm{Cl}_{6},(\mathrm{f})\left[\mathrm{IF}_{6}\right]^{+},(\mathrm{g}) \mathrm{Br} \mathrm{F}_{5}\)
Problem 10
(a) Assuming static structures and no observed coupling to the central atom, what would you expect to see in the \(^{19} \mathrm{F}\) NMR spectra of \(\mathrm{BrF}_{5}\) and \(\left[\mathrm{IF}_{6}\right]^{+} ?\) (b) Do you expect these spectra to be temperature-dependent?
Problem 11
Discuss the interpretation of each of the following observations: (a) \(\mathrm{Al}_{2} \mathrm{Cl}_{6}\) and \(\mathrm{I}_{2} \mathrm{Cl}_{6}\) are not isostructural. (b) Thermal decomposition of \(\left[\mathrm{Bu}_{4} \mathrm{N}\right][\mathrm{ClHI}]\) yields \(\left[\mathrm{Me}_{4} \mathrm{N}\right] \mathrm{I}\) and \(\mathrm{HCl}\) (c) 0.01 m solutions of \(I_{2}\) in \(n\) -hexane, benzene, ethanol and pyridine are violet, purple, brown and yellow respectively. When 0.001 mol of pyridine is added to \(100 \mathrm{cm}^{3}\) of each of the solutions of \(\mathrm{I}_{2}\) in \(n\) -hexane benzene and ethanol, all become yellow.
Problem 14
Suggest likely structures for (a) \(\left[\mathrm{F}_{2} \mathrm{ClO}_{2}\right]^{-},(\mathrm{b}) \mathrm{FBrO}_{3}\) (c) \(\left[\mathrm{ClO}_{2}\right]^{+},(\mathrm{d})\left[\mathrm{F}_{4} \mathrm{ClO}\right]^{-}\)
Problem 17
Suggest products for the following (which are not balanced): (a) \(\left[\mathrm{ClO}_{3}\right]^{-}+\mathrm{Fe}^{2+}+\mathrm{H}^{+} \rightarrow\) (b) \(\left[\mathrm{IO}_{3}\right]^{-}+\left[\mathrm{SO}_{3}\right]^{2-} \rightarrow\) \((\mathrm{c})\left[\mathrm{IO}_{3}\right]^{-}+\mathrm{Br}^{-}+\mathrm{H}^{+} \rightarrow\)
Problem 19
Discuss the interpretation of each of the following observations: (a) Although the hydrogen bonding in HF is stronger than that in \(\mathrm{H}_{2} \mathrm{O}\), water has much the higher boiling point. (b) Silver chloride and silver iodide are soluble in saturated aqueous KI, but insoluble in saturated aqueous KCl.
Problem 23
(a) BrO has been detected in the emission gases from volcanoes (N. Bobrowski et al. (2003) Nature, vol. \(423,\) p. 273 ). Construct an MO diagram for the formation of BrO from Br and O atoms. Comment on any properties and bonding features of BrO that you can deduce from the diagram. (b) \(\left[\mathrm{Cl}_{2} \mathrm{O}_{2}\right]^{+}\) is approximately planar and is described as a charge transfer complex of \(\left[\mathrm{Cl}_{2}\right]^{+}\) and \(\mathrm{O}_{2} .\) By considering the HOMOs and LUMOs of \(\left[\mathrm{Cl}_{2}\right]^{+}\) and \(\mathrm{O}_{2},\) suggest what orbital interactions are involved in the charge transfer.
