Chapter 22

When NaCl dissolves in water, which molecules or ions occupy the inner coordination sphere around the \(\mathrm{Na}^{+}\) ions?

When \(\operatorname{Cr}\left(\mathrm{NO}_{3}\right)_{3}\) dissolves in water, which of the following species are nearest the \(\mathrm{Cr}^{3+}\) ions? a. Other \(\mathrm{Cr}^{3+}\) ions b. \(\mathrm{NO}_{3}^{-}\) ions c. \(\mathrm{H}_{2} \mathrm{O}\) molecules with the \(\mathrm{O}\) atoms closest to the \(\mathrm{Cr}^{3+}\) d. \(\mathrm{H}_{2} \mathrm{O}\) molecules with the \(\mathrm{H}\) atoms closest to the \(\mathrm{Cr}^{3+}\)

When \(\left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{6}\right] \mathrm{Cl}_{2}\) dissolves in water, which molecules or ions occupy the inner coordination sphere around the \(\mathrm{Ni}^{2+}\) ions?

Which ion is the counterion in the coordination compound \(\mathrm{Na}_{2}\left[\mathrm{Zn}(\mathrm{CN})_{4}\right] ?\)

Which ion is the counterion in the coordination compound \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{4} \mathrm{Cl}_{2}\right] \mathrm{NO}_{3} ?\)

What are the names of the following complex ions? a. \(\operatorname{Cr}\left(\mathrm{NH}_{3}\right)_{6}^{3+}\) b. \(\operatorname{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}^{3+}\) c. \(\left[\mathrm{Fe}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Cl}\right]^{2+}\)

What are the names of the following complex ions? a. \(\mathrm{Cu}\left(\mathrm{NH}_{3}\right)_{2}^{+}\) b. \(\operatorname{Ti}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}(\mathrm{OH})_{2}^{2+}\) c. \(\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{4}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}^{2+}\)

What are the names of the following complex ions? a. \(\operatorname{CoBr}_{4}^{2-}\) b. \(\mathrm{Zn}\left(\mathrm{H}_{2} \mathrm{O}\right)(\mathrm{OH})_{3}-\) c. \(\mathrm{Ni}(\mathrm{CN})_{5}^{3-}\)

What are the names of the following complex ions? a. \(\mathrm{CoI}_{4}^{2}\) b. \(\mathrm{CuCl}_{4}^{2-}\) c. \(\left[\mathrm{Cr}(\text { en })(\mathrm{OH})_{4}\right]^{-}\)

What are the names of the following coordination compounds? a. \(\left[\mathrm{Zn}(\mathrm{en})_{2}\right] \mathrm{SO}_{4}\) b. \(\left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{H}_{2} \mathrm{O}\right)\right] \mathrm{Cl}_{2}\) c. \(\mathrm{K}_{4}\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\)

What are the names of the following coordination compounds? a. \(\left(\mathrm{NH}_{4}\right)_{3}\left[\mathrm{Co}(\mathrm{CN})_{6}\right]\) b. \(\left[\mathrm{Co}(\mathrm{en})_{2} \mathrm{Cl}\right]\left(\mathrm{NO}_{3}\right)_{2}\) c. \(\left[\mathrm{Fe}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}(\mathrm{OH})_{2}\right] \mathrm{Cl}\)

What is meant by the term sequestering agent? What properties make a substance an effective sequestering agent?

How does the chelating ability of an aminocarboxylic acid vary with changing pH?

Food Preservative The EDTA that is widely used as a food preservative is added to food, not as the undissociated acid, but rather as the calcium disodium salt: \(\mathrm{Na}_{2}[\mathrm{CaEDTA}]\) This salt is actually a coordination compound with a \(\mathrm{Ca}^{2+}\) ion at the center of a complex ion. Draw the structure of this compound.

Explain why the compounds of most of the first-row transition metals are colored.

Unlike the compounds of most transition metal ions, those of \(\mathrm{Ti}^{4+}\) are colorless. Why?

Why is the \(d_{x y}\) orbital higher in energy than the \(d_{x z}\) and \(d_{y z}\) orbitals in a square planar crystal field?

On average, the \(d\) orbitals of a transition metal ion in an octahedral field are higher in energy than they are when the ion is in the gas phase. Why?

Aqueous solutions of one of the following complex ions of chromium(III) are violet; solutions of the other are yellow. Which is which? (a) \(\operatorname{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}^{3+} ;\) (b) \(\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{6}^{3+}\)

Which of the following complex ions should absorb the shortest wavelengths of electromagnetic radiation? (a) \(\mathrm{CuCl}_{4}^{2-} ;\) (b) \(\mathrm{CuF}_{4}^{2-} ;\) (c) \(\mathrm{CuI}_{4}^{2-} ;\) (d) \(\mathrm{CuBr}_{4}^{2-}\)

The octahedral crystal field splitting energy \(\Delta_{0}\) of \(\mathrm{Co}(\mathrm{CN})_{6}^{3-}\) is \(6.74 \times 10^{-19} \mathrm{J} / \mathrm{ion.}\) What is the color of a solution of this complex ion?

Solutions of \(\mathrm{NiCl}_{4}^{2-}\) and \(\mathrm{NiBr}_{4}^{2-}\) absorb light at \(702 \mathrm{nm}\) and \(756 \mathrm{nm},\) respectively. In which ion is the split of \(d\) -orbital energies greater?

What determines whether a transition metal ion is in a bigh-spin configuration or a low-spin configuration?

Would you expect a solution of a high-spin complex of a transition metal ion to be the same color as a solution of a low-spin complex? Why?

How many unpaired electrons are there in the following transition metal ions in an octahedral field? High-spin \(\mathrm{Fe}^{2+}, \mathrm{Cu}^{2+}, \mathrm{Co}^{2+},\) and \(\mathrm{Mn}^{3+}\)

Which of the following cations can have either a high-spin or a low-spin electron configuration in an octahedral field? \(\mathrm{Fe}^{2+}, \mathrm{Co}^{3+}, \mathrm{Mn}^{2+},\) and \(\mathrm{Cr}^{3+}\)

Which of the following cations can, in principle, have either a high-spin or a low-spin electron configuration in a tetrahedral field? \(\mathrm{Co}^{2+}, \mathrm{Cr}^{3+}, \mathrm{Ni}^{2+},\) and \(\mathrm{Zn}^{2+}\)

How many unpaired electrons are in the following transition metal ions in an octahedral crystal field? High-spin \(\mathrm{Fe}^{3+}, \mathrm{Rh}^{+}, \mathrm{V}^{3+},\) and low-spin \(\mathrm{Mn}^{3+}\)

The manganese minerals pyrolusite, \(\mathrm{MnO}_{2},\) and hausmannite, \(\mathrm{Mn}_{3} \mathrm{O}_{4},\) contain manganese ions surrounded by oxide ions. a. What are the charges of the Mn ions in each mineral? b. In which of these compounds could there be high-spin and low-spin Mn ions?

Dietary Supplement Chromium picolinate is an over-thecounter dict aid sold in many pharmacics. The \(\mathrm{Cr}^{3+}\) ions in this coordination compound are in an octahedral field. Is the compound paramagnetic or diamagnetic?

Refining Cobalt One method for refining cobalt involves the formation of the complex ion \(\mathrm{CoCl}_{4}^{2-} .\) This anion is tetrahedral. Is this complex paramagnetic or diamagnetic?

Why is it that \(\mathrm{Ni}(\mathrm{CN})_{4}^{2-}\) is diamagnetic, but \(\mathrm{NiCl}_{4}^{2-}\) is paramagnetic?

What do the prefixes cis- and trans-mean in the context of an octahedral complex ion?

What do the prefixes cis- and trans-mean in the context of a square planar complex?

What minimum number of donor groups are required in order to have stereoisomers of a square planar complex?

Does the complex \(\mathrm{Co}(\mathrm{en})\left(\mathrm{H}_{2} \mathrm{O}\right)_{2} \mathrm{Cl}_{2}\) have stereoisomers?

Does the complex ion \(\mathrm{Fe}(\mathrm{en})_{3}^{3+}\) have stereoisomers?

Sketch the stereoisomers of the square planar complex ion \(\mathrm{CuCl}_{2} \mathrm{Br}_{2}^{2-} .\) Are any of these isomers chiral?

Sketch the stercoisomers of the complex ion \(\mathrm{Ni}(\mathrm{en}) \mathrm{Cl}_{2}(\mathrm{CN})_{2}^{2-} .\) Are any of these isomers chiral?

Enzymes are large proteins. a. What is the function of enzymes? b. Are all proteins enzymes?

Why is \(\mathrm{Cd}^{2+}\) more likely than \(\mathrm{Cr}^{2+}\) to replace \(\mathrm{Zn}^{2+}\) in an enzyme such as carbonic anhydrase?

What effect does an enzyme have on the activation energy of a biochemical reaction?

Why might reductases also be described as reducing agents?

When a transition metal ion such as \(\mathrm{Cu}^{2+}\) is incorporated into a metalloenzyme, is the formation constant likely to be much greater than one \((K \gg 1)\) or much less than one \((K<<1) ?\) \(\mathrm{Cu}^{2+}+\) protein \(\rightleftharpoons\) metalloenzyme \(\quad K=\frac{[\text { metalloenzyme }]}{\left[\mathrm{Cu}^{2+}\right][\text { protein }]}\)

Carbon monoxide poisoning derives from competitive binding of CO versus \(\mathrm{O}_{2}\) to the \(\mathrm{Fe}^{2+}\) in the coordination sphere of hemoglobin. If CO can be displaced by breathing pure \(\mathrm{O}_{2},\) which of the following is likely to be correct under these conditions: \(\mathrm{K}_{\mathrm{O}} / \mathrm{K}_{\mathrm{CO}}<1\) or \(\mathrm{K}_{\mathrm{O}} / \mathrm{K}_{\mathrm{CO}}>1 ?\)

The activation energy for the uncatalyzed decomposition hydrogen peroxide at \(20^{\circ} \mathrm{C}\) is \(75.3 \mathrm{kJ} / \mathrm{mol}\). In the presence of the enzyme catalase, the activation energy is reduced to \(29.3 \mathrm{kJ} / \mathrm{mol} .\) By using the following form of the Arrhenius equation, \(R T \ln \left(k_{1} / k_{2}\right)=E_{x_{2}}-E_{\mathrm{a}_{1}},\) how much faster is the catalyzed reaction?

Under what circumstances might a coordination complex of a toxic metal be useful in medicine?

Cancer Treatment Brachiotherapy is a cancer treatment that involves surgical implantation of a small capsule of 192 Ir into a tumor. Iridium-192 lies between two stable isotopes of iridium, \(^{193}\) Ir and \(^{191}\) Ir. How does this account for the fact that \(^{192}\) Ir decays by \(\beta\) decay, electron capture, and positron emission?

Gadolinium-153 decays by electron capture. What type of radiation does \(^{153}\) Gd produce that makes it useful for imaging?

Gadolinium-153 and samarium-153 both have the same mass number. Why might \(^{153}\) Gd decay by electron capture, whereas 153 Sm decays by emitting \(\beta\) particles?