Problem 12
(a) Explain why the reaction of \(\mathrm{SF}_{4}\) with \(\mathrm{BF}_{3}\) yields \(\left[\mathrm{SF}_{3}\right]^{+},\) whereas the reaction with \(\mathrm{CsF}\) gives \(\mathrm{Cs}\left[\mathrm{SF}_{5}\right]\) (b) Suggest how \(\mathrm{SF}_{4}\) might react with a carboxylic acid, \(\mathrm{RCO}_{2} \mathrm{H}\)
Problem 14
Discuss the trends in (a) the \(\mathrm{O}-\mathrm{O}\) bond lengths in \(\mathrm{O}_{2}\) \((121 \mathrm{pm}),\left[\mathrm{O}_{2}\right]^{+}(112 \mathrm{pm}), \mathrm{H}_{2} \mathrm{O}_{2}(147.5 \mathrm{pm}),\left[\mathrm{O}_{2}\right]^{2-}\) \((149 \mathrm{pm})\) and \(\mathrm{O}_{2} \mathrm{F}_{2}(122 \mathrm{pm}),\) and (b) the \(S-S\) bond distances in \(\mathrm{S}_{6}(206 \mathrm{pm}), \mathrm{S}_{2}(189 \mathrm{pm}),\left[\mathrm{S}_{4}\right]^{2+}(198 \mathrm{pm})\) \(\mathrm{H}_{2} \mathrm{S}_{2}(206 \mathrm{pm}), \mathrm{S}_{2} \mathrm{F}_{2}(189 \mathrm{pm}), \mathrm{S}_{2} \mathrm{F}_{10}(221 \mathrm{pm})\) and \(\mathrm{S}_{2} \mathrm{Cl}_{2}\) \((193 \mathrm{pm}) \cdot\left[\text { Data: } r_{\mathrm{cov}}(\mathrm{S})=103 \mathrm{pm} .\right]\)
Problem 15
Comment on the following values of gas-phase dipole moments: \(\operatorname{Se} \mathrm{F}_{6}, 0 \mathrm{D} ; \mathrm{SeF}_{4}, 1.78 \mathrm{D} ; \mathrm{SF}_{4}, 0.64 \mathrm{D} ; \mathrm{SCl}_{2}\) \(0.36 \mathrm{D} ; \mathrm{SOCl}_{2}, 1.45 \mathrm{D} ; \mathrm{SO}_{2} \mathrm{Cl}_{2}, 1.81 \mathrm{D}\)
Problem 17
In the following series of compounds or ions, identify those that are isoelectronic (with respect to the valence electrons and those that are also isostructural: (a) \(\left[\mathrm{SiO}_{4}\right]^{4-},\left[\mathrm{PO}_{4}\right]^{3-},\left[\mathrm{SO}_{4}\right]^{2-} ;\) (b) \(\mathrm{CO}_{2}, \mathrm{SiO}_{2}, \mathrm{SO}_{2}, \mathrm{TeO}_{2}\) \(\left[\mathrm{NO}_{2}\right]^{+} ;(\mathrm{c}) \mathrm{SO}_{3},\left[\mathrm{PO}_{3}\right]^{-}, \mathrm{SeO}_{3} ;(\mathrm{d})\left[\mathrm{P}_{4} \mathrm{O}_{12}\right]^{4-}, \mathrm{Se}_{4} \mathrm{O}_{12}\) \(\left[\mathrm{Si}_{4} \mathrm{O}_{12}\right]^{8}\).
Problem 18
(a) Give the structures of \(\mathrm{SO}_{3}\) and \(\left[\mathrm{SO}_{3}\right]^{2-}\) and rationalize the difference between them. (b) Outline the properties of aqueous solutions of \(\mathrm{SO}_{2}\) and discuss the species that can be derived from them.
Problem 20
Discuss the interpretation of each of the following observations. (a) When metallic Cu is heated with concentrated \(\mathrm{H}_{2} \mathrm{SO}_{4},\) in addition to \(\mathrm{CuSO}_{4}\) and \(\mathrm{SO}_{2},\) some CuS is formed. (b) The \(\left[\mathrm{TeF}_{5}\right]^{-}\) ion is square pyramidal. (c) Silver nitrate gives a white precipitate with aqueous sodium thiosulfate; the precipitate dissolves in an excess of \(\left[\mathrm{S}_{2} \mathrm{O}_{3}\right]^{2-}\). If the precipitate is heated with water, it turns black, and the supernatant liquid then gives a white precipitate with acidified aqueous \(\mathrm{Ba}\left(\mathrm{NO}_{3}\right)_{2}\)
Problem 22
The action of concentrated \(\mathrm{H}_{2} \mathrm{SO}_{4}\) on urea, \(\left(\mathrm{H}_{2} \mathrm{N}\right)_{2} \mathrm{CO}\) results in the production of a white crystalline solid \(\mathbf{X}\) of formula \(\mathrm{H}_{3} \mathrm{NO}_{3} \mathrm{S}\). This is a monobasic acid. On treatment with sodium nitrite and dilute hydrochloric acid at \(273 \mathrm{K}\) one mole of \(\mathbf{X}\) liberates one mole of \(\mathrm{N}_{2},\) and on addition of aqueous \(\mathrm{BaCl}_{2},\) the resulting solution yields one mole of \(\mathrm{BaSO}_{4}\) per mole of \(\mathbf{X}\) taken initially. Deduce the structure of \(\mathbf{X}\)
Problem 23
Write a brief account of the oxoacids of sulfur, paying particular attention to which species are isolable.
Problem 24
Give the structures of \(\mathrm{S}_{2} \mathrm{O},\left[\mathrm{S}_{2} \mathrm{O}_{3}\right]^{2-}, \mathrm{NSF}, \mathrm{NSF}_{3},\left[\mathrm{NS}_{2}\right]^{+}\) and \(\mathrm{S}_{2} \mathrm{N}_{2}\) and rationalize their shapes.
Problem 25
\(\left[\mathrm{NS}_{2}\right]\left[\mathrm{SbF}_{6}\right]\) reacts with nitriles, \(\mathrm{RC} \equiv \mathrm{N},\) to give \([\mathrm{X}]\left[\mathrm{SbF}_{6}\right]\) where \([\mathbf{X}]^{+}\) is a cycloaddition product. Propose a structure for \([\mathbf{X}]^{+}\) and show that it is a \(6 \pi\) -electron system. Do you expect the ring to be planar or puckered? Give reasons for your answer.
