Problem 1
Review what is meant by the following terms: (a) elementary step, (b) rate-determining step, (c) activation energy, (d) intermediate, (e) transition state, (f) rate equation, (g) zero, first and second order rate laws, (h) nucleophile.
Problem 7
The reaction of trans\(=\left[\mathrm{Pt}\left(\mathrm{PEt}_{3}\right)_{2} \mathrm{PhCl}\right]\) with the strong nucleophile thiourea (tu) in MeOH follows a 2 -term rate law with \(k_{\text {obs }}=k_{1}+k_{2}[\mathrm{tu}] .\) A plot of \(k_{\text {obs }}\) against [tu] is linear with the line passing close to the origin. Rationalize these observations.
Problem 10
(a) Rationalize the formation of the products in the following sequence of reactions: \\[ \begin{aligned} \left[\operatorname{Rh}\left(\mathrm{OH}_{2}\right)_{6}\right]^{3+} \frac{\mathrm{C}^{-}}{-\mathrm{H}_{2} \mathrm{O}}-\left[\operatorname{Rh} \mathrm{Cl}\left(\mathrm{OH}_{2}\right)_{5}\right]^{2+} & \\ & \frac{\mathrm{C}^{-}}{-\mathrm{H}_{2} \mathrm{O}}-\operatorname{trans}-\left[\mathrm{RhCl}_{2}\left(\mathrm{OH}_{2}\right)_{4}\right]^{+} \\\ & \frac{\mathrm{C}^{+}}{-\mathrm{H}_{2} \mathrm{O}^{-} \operatorname{mer} \cdot\left[\mathrm{RhCl}_{3}\left(\mathrm{OH}_{2}\right)_{3}\right]} \\ & \frac{\mathrm{C}^{-}}{-\mathrm{H}_{2} 0}-\operatorname{trans}-\left[\mathrm{RhCl}_{4}\left(\mathrm{OH}_{2}\right)_{2}\right]^{-} \end{aligned} \\] (b) Suggest methods of preparing \(\left[\mathrm{RhCl}_{5}\left(\mathrm{OH}_{2}\right)\right]^{2-},\) cis\(\left[\mathrm{RhCl}_{4}\left(\mathrm{OH}_{2}\right)_{2}\right]^{-}\) and \(f a c \cdot\left[\mathrm{RhCl}_{3}\left(\mathrm{OH}_{2}\right)_{3}\right]\)
Problem 11
What reason can you suggest for the sequence \(\mathrm{Co}>\mathrm{Rh}>\mathrm{Ir}\) in the rates of anation of \(\left[\mathrm{M}\left(\mathrm{OH}_{2}\right)_{6}\right]^{3+}\) ions?
Problem 13
Suggest a mechanism for the possible racemization of tertiary amines \(\mathrm{NR}_{1} \mathrm{R}_{2} \mathrm{R}_{3}\). Is it likely that such molecules can be resolved?
Problem 14
The rate of racemization of \(\left[\mathrm{CoL}_{1}\right]\) where \(\mathrm{HL}=26.11 \mathrm{a}\) is approximately the same as its rate of isomerization into \(\left[\mathrm{CoL}_{3}^{\prime}\right]\) where \(\mathrm{HL}^{+}=26.11 \mathrm{b} .\) What can you deduce about the mechanisms of these reactions?
Problem 16
Rationalize the observation that when the reaction: \\[ \begin{aligned} \left[\operatorname{Co}\left(\mathrm{NH}_{3}\right)_{4}\left(\mathrm{CO}_{3}\right)\right]^{+} & \\ \frac{\left[\mathrm{H}_{3} \mathrm{O}^{+}, \mathrm{H}_{2} \mathrm{O}\right.}{\longrightarrow}\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4}\left(\mathrm{OH}_{2}\right)_{2}\right]^{3+}+\mathrm{CO}_{2} \end{aligned} \\] is carried out in \(\mathrm{H}_{2}\left(^{18} \mathrm{O}\right)\), the water in the complex contains equal proportions of \(\mathrm{H}_{2}\left(^{18} \mathrm{O}\right)\) and \(\mathrm{H}_{2}\left(^{16} \mathrm{O}\right)\)
Problem 18
The rate constants for racemization \(\left(k_{r}\right)\) and dissociation \(\left(k_{d}\right)\) of \(\left[\mathrm{FeL}_{3}\right]^{4-}\left(\mathrm{H}_{2} \mathrm{L}=26.12\right)\) at several temperatures, \(T\) are given in the table. (a) Determine \(\Delta H^{\dagger}\) and \(\Delta S^{\dagger}\) for each reaction. (b) What can you deduce about the mechanism of racemization? $$\begin{array}{llllll} T / \mathrm{K} & 288 & 294 & 298 & 303 & 308 \\ k_{\mathrm{r}} \times 10^{5} / \mathrm{s}^{-1} & 0.5 & 1.0 & 2.7 & 7.6 & 13.4 \\\ k_{\mathrm{d}} \times 10^{5} / \mathrm{s}^{-1} & 0.5 & 1.0 & 2.8 & 7.7 & 14.0 \end{array}$$
Problem 19
The reaction: \(\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Cl}\right]^{2+}+\mathrm{NH}_{3}-=\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{6}\right]^{3+}+\mathrm{Cl}^{-}\) in liquid \(\mathrm{NH}_{3}\) is catalysed by \(\mathrm{KNH}_{2}\), Suggest an explanation for this observation.
Problem 21
Discuss, with examples, the differences between innerand outer-sphere mechanisms, and state what is meant by a self-exchange reaction.
