Chapter 26

When a transition metal atom forms an ion, which electrons are lost first?

Explain why transition metals exhibit multiple oxidation states instead of a single oxidation state (like most of the main-group metals).

Briefly define each term. a. coordination number b. ligand c. bidentate and polydentate d. complex ion e. chelating agent

Using the Lewis acid-base definition, how would you categorize a ligand? How would you categorize a transition metal ion?

Explain the differences between each pair of isomer types. a. structural isomer and stereoisomer b. linkage isomer and coordination isomer c. geometric isomer and optical isomer

Which complex ion geometry has the potential to exhibit cistrans isomerism: linear, tetrahedral, square planar, octahedral?

Explain the differences between weak-field and strong-field metal complexes.

Explain why compounds of \(\mathrm{Sc}^{3+}\) are colorless, but compounds of \(\mathrm{Ti}^{3+}\) are colored.

Explain the differences between high-spin and low-spin metal complexes.

Many transition metal compounds are colored. How does crystal field theory account for this?

Write the ground state electron configuration for each atom and ion pair. = a. \(\mathrm{Ni}, \mathrm{Ni}^{2+}\) b. \(\mathrm{Mn}, \mathrm{Mn}^{4+}\) c. \(Y, Y^{+}\) d. \(\mathrm{Ta}, \mathrm{Ta}^{2+}\)

Write the ground state electron configuration for each atom and ion pair. a. \(\mathrm{Zr}, \mathrm{Zr}^{2+}\) b. \(\mathrm{Co}, \mathrm{Co}^{2+}\) c. \(\mathrm{Tc}, \mathrm{Tc}^{3+}\) d. Os, \(\mathrm{Os}^{4+}\)

Determine the highest possible oxidation state for each element. 26.2 a. V b. Re C. \(Pd\)

Which first-row transition metal(s) has the following highest possible oxidation state? a. +3 b. +7 c. +4

Determine the oxidation state and coordination number of the metal ion in each complex ion. a. \(\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}\) b. \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right]^{-}\) c. \(\left[\mathrm{Cu}(\mathrm{CN})_{4}\right]^{2-}\) d. \(\left[\mathrm{Ag}\left(\mathrm{NH}_{3}\right)_{2}\right]^{+}\)

Determine the oxidation state and coordination number of the metal ion in each complex ion. a. \(\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Br}\right]^{2+}\) b. \(\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4-}\) c. \(\left[\mathrm{Co}(\mathrm{ox})_{3}\right]^{4-}\) d. \(\left[\mathrm{PdCl}_{4}\right]^{2-}\)

Name each complex ion or coordination compound. a. \(\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{6}\right]^{3+}\) b. \(\left[\mathrm{Cu}(\mathrm{CN})_{4}\right]^{2-}\) c. \(\left[\mathrm{Fe}\left(\mathrm{NH}_{3}\right)_{5} \mathrm{Br}\right] \mathrm{SO}_{4}\) d. \(\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}\left(\mathrm{NH}_{3}\right)(\mathrm{OH})\right] \mathrm{Cl}_{2}\)

Name each complex ion or coordination compound. a. \(\left[\mathrm{Cu}(\mathrm{en})_{2}\right]^{2+}\) b. \(\left[\mathrm{Mn}(\mathrm{CO})_{3}\left(\mathrm{NO}_{2}\right)_{3}\right]^{2+}\) c. \(\operatorname{Na}\left[\operatorname{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}(\mathrm{ox})_{2}\right]\) d. \(\left[\mathrm{Co}(\mathrm{en})_{3}\right]\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]\)

Write the formula for each complex ion or coordination compound. a. hexaamminechromium(III) b. potassium hexacyanoferrate(III) c. ethylenediaminedithiocyanatocopper(II) d. tetraaquaplatinum(II) hexachloroplatinate(IV)

Write the formula for each complex ion or coordination compound. a. hexaaquanickel(II) chloride b. pentacarbonylchloromanganese(I) c. ammonium diaquatetrabromovanadate(III) d. tris(ethylenediamine) cobalt(III) trioxalatoferrate(III)

Write the formula and the name of each complex ion or coordination compound. a. a complex ion with four water molecules and two \(\mathrm{ONO}^{-}\) ions connected to an Fe(III) ion b. a coordination compound made of two complex ions: one a complex of \(\mathrm{V}\) (III) with two ethylenediamine molecules and two \(\mathrm{Cl}^{-}\) ions as ligands and the other a complex of \(\mathrm{Ni}(\mathrm{II})\) having a coordination number of 4 with \(\mathrm{Cl}^{-}\) ions as ligands

Draw two linkage isomers of \(\left[\mathrm{Mn}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{NO}_{2}\right)\right]^{2+}\)

Which complexes exhibit geometric isomerism? a. \(\left[\mathrm{Cr}\left(\mathrm{NH}_{3}\right)_{5}(\mathrm{OH})\right]^{2+}\) b. \(\left[\mathrm{Cr}(\mathrm{en})_{2} \mathrm{Cl}_{2}\right]^{+}\) c. \(\left[\mathrm{Cr}\left(\mathrm{H}_{2} \mathrm{O}\right)\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{2}\right]^{+}\) d. \(\left[\mathrm{Pt}\left(\mathrm{NH}_{3}\right) \mathrm{Cl}_{3}\right]^{-}\) e. \(\left[\mathrm{Pt}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}(\mathrm{CN})_{2}\right]\)

Which complexes exhibit geometric isomerism? a. \(\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2 (\mathrm{ox})_{2}\right]^{-}\) b. \(\left[\mathrm{Co}(\mathrm{en})_{3}\right]^{3+}\) c. \(\left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}\left(\mathrm{NH}_{3}\right)_{2}(\mathrm{ox})\right]^{+}\) d. \(\left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{2}(\mathrm{en})\right]^{2+}\) e. \(\left[\mathrm{Ni}(\mathrm{CO})_{2} \mathrm{Cl}_{2}\right]\)

If \(\mathrm{W}, \mathrm{X}, \mathrm{Y},\) and \(\mathrm{Z}\) are different monodentate ligands, how many geometric isomers are there for each ion? a. square planar \([\mathrm{NiWXYZ}]^{2+}\) b. tetrahedral \([\mathrm{ZnWXYZ}]^{2+}\)

Draw the structures and label the type for all the isomers of each ion. a. \(\left[\mathrm{Cr}(\mathrm{CO})_{3}\left(\mathrm{NH}_{3}\right)_{3}\right]^{3+}\) b. \(\left[\mathrm{Pd}(\mathrm{CO})_{2}\left(\mathrm{H}_{2} \mathrm{O}\right) \mathrm{Cl}\right]^{+}\)

Draw the octahedral crystal field splitting diagram for each metal ion. a. \(\mathrm{Cr}^{3+}\) b. \(\mathrm{Cu}^{2+}\) c. \(\mathrm{Mn}^{3+}\) (high-and low-spin) d. \(\mathrm{Fe}^{2+}\) (low-spin)

The \(\left[\mathrm{CrCl}_{6}\right]^{3-}\) ion has a maximum in its absorption spectrum at \(735 \mathrm{nm} .\) Calculate the crystal field splitting energy (in \(\mathrm{kJ} / \mathrm{mol}\) ) for this ion.

How many unpaired electrons would you expect for each complex ion? a. \(\left[\mathrm{Cr}(\mathrm{CN})_{6}\right]^{4-}\) b. \(\left[\mathrm{MnF}_{6}\right]^{4-}\) c. \(\left[\mathrm{Ru}(\mathrm{en})_{3}\right]^{2+}\)

The complex ion \(\left[\mathrm{PdCl}_{4}\right]^{2-}\) is known to be diamagnetic. Use this information to determine if it is a tetrahedral or square planar structure.

What structural feature do hemoglobin, cytochrome \(c,\) and chlorophyll have in common?

Carbon monoxide and the cyanide ion are both toxic because they bind more strongly than oxygen to the iron in hemoglobin (Hb). $$\begin{array}{ll}\mathrm{Hb}+\mathrm{O}_{2} \rightleftharpoons \mathrm{HbO}_{2} & K=2 \times 10^{12} \\\\\mathrm{Hb}+\mathrm{CO} \rightleftharpoons \mathrm{HbCO} & K=1 \times 10^{14}\end{array}$$Calculate the equilibrium constant value for this reaction: $$\mathrm{HbO}_{2}+\mathrm{CO} \rightleftharpoons \mathrm{HbCO}+\mathrm{O}_{2} $$Does the equilibrium favor reactants or products?

Recall from Chapter 9 that \(\mathrm{Cr}\) and \(\mathrm{Cu}\) are exceptions to the normal orbital filling, resulting in a [Ar] \(4 s^{1} 3 d^{x}\) configuration. Write the ground state electron configuration for each species. a. \(\mathrm{Cr}, \mathrm{Cr}^{+}, \mathrm{Cr}^{2+}, \mathrm{Cr}^{3+}\) b. \(\mathrm{Cu}, \mathrm{Cu}^{+}, \mathrm{Cu}^{2+}\)

Most of the second row transition metals do not follow the normal orbital filling pattern. Five of them \(-\mathrm{Nb}, \mathrm{Mo}, \mathrm{Ru}, \mathrm{Rh},\) and Ag-have a \([\mathrm{Kr}] 5 s^{1} 4 d^{x}\) configuration and \(\mathrm{Pd}\) has a \([\mathrm{Kr}] 4 d^{10}\) configuration. Write the ground state electron configuration for each species. a. \(\mathrm{Mo}, \mathrm{Mo}^{+}, \mathrm{Ag}, \mathrm{Ag}^{+}\) b. \(\mathrm{Ru}, \mathrm{Ru}^{3+}\) c. \(\mathrm{Rh}, \mathrm{Rh}^{2+}\) d. \(\mathrm{Pd}, \mathrm{Pd}^{+}, \mathrm{Pd}^{2+}\)

Hexacyanomanganate(III) ion is a low-spin complex. Draw the crystal field splitting diagram with electrons filled in appropriately. Is this complex paramagnetic or diamagnetic?

Draw the structures of all the geometric isomers of \(\left[\mathrm{Ru}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}\left(\mathrm{NH}_{3}\right)_{2} \mathrm{Cl}_{2}\right]^{+} .\) Draw the mirror images of any that are chiral.

Draw a crystal field splitting diagram for a trigonal planar complex ion. Assume the plane of the molecule is perpendicular to the \(z\) -axis.

Explain why \(\left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{4}\right]^{2+}\) is paramagnetic, while \(\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}\) is diamagnetic.

Sulfide \(\left(\mathrm{S}^{2-}\right)\) salts are notoriously insoluble in aqueous solution. a. Calculate the molar solubility of nickel(II) sulfide in water.$$K_{\mathrm{sp}}(\mathrm{NiS})=3 \times 10^{-16}$$ b. Nickel(II) ions form a complex ion in the presence of ammonia with a formation constant \(\left(K_{f}\right)\) of \(2.0 \times 10^{8}\) :\(\mathrm{Ni}^{2+}+6\mathrm{NH}_{3}\rightleftharpoons\left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{6}\right]^{2+}\). Calculatethe molar solu-bility of NiS in \(3.0 \mathrm{M} \mathrm{NH}_{3}\) c. Explain any differences between the answers to parts a and b.

Which element has the higher ionization energy, Cu or Au?

The complexes of \(\mathrm{Fe}^{3+}\) have magnetic properties that depend on whether the ligands are strong or weak field. Explain why this observation supports the idea that electrons are lost from the \(4 s\) orbital before the \(3 d\) orbitals in the transition metals.

Choose a row of the transition metals in the periodic table. Have each group member look up and graph (where appropriate) a separate trend for the elements in that row, choosing from electron configuration, atomic size, ionization energy, and electronegativity. Each member should present a graph to the group and describe the general trend and any notable exceptions. If possible, form new groups made up of individuals who researched the same property for different rows of the periodic table.

Have each group member write down the names and formulas for two coordination compounds. Taking turns, show each formula to the group and have the rest of the group name the compound, with each member contributing one step in the process. Once all group members have had their formulas named, repeat the process by showing each formula name to the group and having group members determine the correct formula.