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- Complete the exercises below. Determine if each of the following metal complexes is chiral and therefore has an optical isomer: a. square planar [Pd(en)(CN)₂].
Problem 46
- Complete the exercises below. a. If a complex absorbs light at 610 nm, what color would you expect the complex to be? b. What is the energy in joules of a photon with a wavelength of 610 nm? c. What is the energy of this absorption in kJ/mol?
Problem 47
- Complete the exercises below. a. A complex absorbs photons with an energy of 4.51 x 10⁻¹⁹ J. What is the wavelength of these photons? b. If this is the only place in the visible spectrum where the complex absorbs light, what color would you expect the complex to be?
Problem 48
- Complete the exercises below. Identify each of the following coordination complexes as either diamagnetic or paramagnetic: a. [ZnCl₄]²⁻ b. [Pd(NH₃)₂ Cl₂]
Problem 49
Problem 52a
The lobes of which d orbitals point directly between the ligands in a. octahedral geometry,
Problem 52b
The lobes of which d orbitals point directly between the ligands in b. tetrahedral geometry?
Problem 54
As shown in Figure 23.26, the d-d transition of [Ti(H2O)6]³⁺ produces an absorption maximum at a wavelength of about 500 nm .
a. What is the magnitude of ∆ for [Ti(H2O)6]³⁺ in kJ/mol?
b. How would the magnitude of ∆ change if the H2O ligands in [Ti(H2O)6]]³⁺ were placed with NH3 ligands?
- Complete the exercises below. Give the number of (valence) d electrons associated with the central metal ion in each of the following complexes: a. K₃[Fe(CN)₆] b. [Mn(H₂O)₆](NO₃)₂ c. Na[Ag(CN)₂] d. [Cr(NH₃)₄Br₂]ClO₄ e. [Sr(EDTA)]²⁻
Problem 58
Problem 59
A classmate says, “A weak-field ligand usually means the complex is high spin.” Is your classmate correct? Explain.
Problem 60
For a given metal ion and set of ligands, is the crystal-field splitting energy larger for a tetrahedral or an octahedral geometry?
- Complete the exercises below. For each of the following metals, write the electronic configuration of the atom and its 3+ ion: a. Fe. Draw the crystal-field energy-level diagram for the d orbitals of an octahedral complex, and show the placement of the d electrons for each 3+ ion, assuming a weak-field complex. How many unpaired electrons are there in each case?
Problem 62
- Complete the exercises below. Draw the crystal-field energy-level diagrams and show the placement of d electrons for each of the following: a. [Cr(H₂O)₆]²⁺ (four unpaired electrons).
Problem 63
Problem 64a,b
Complete the exercises below. Draw the crystal-field energy-level diagrams and show the placement of electrons for each of the following complexes:
a. [VCl6]3–,
b. [FeF6]3– (a high-spin complex),
Problem 64d
Draw the crystal-field energy-level diagrams and show the placement of electrons for each of the following complexes:
d. [NiCl4]2+ (tetrahedral),
- Complete the exercises below. The complex [Mn(NH₃)₆]²⁺ contains five unpaired electrons. Sketch the energy-level diagram for the d orbitals, and indicate the placement of electrons for this complex ion. Is the ion a high-spin or a low-spin complex?
Problem 65
- Complete the exercises below. The ion [Fe(CN)₆]³⁻ has one unpaired electron, whereas [Fe(NCS)₆]³⁻ has five unpaired electrons. From these results, what can you conclude about whether each complex is high spin or low spin? What can you say about the placement of NCS⁻ in the spectrochemical series?
Problem 66
- Complete the exercises below. Explain why the transition metals in periods 5 and 6 have nearly identical radii within each group.
Problem 68
Problem 71a
Sketch the structure of the complex in each of the following compounds and give the full compound name:
a. cis-[Co(NH3)4(H2O)2] (NO3)2
Problem 71b
Sketch the structure of the complex in each of the following compounds and give the full compound name:
b. Na2[Ru(H2O)Cl5]
Problem 71c
Sketch the structure of the complex in each of the following compounds and give the full compound name:
c. trans-NH3[Co(C2O4)2(H2O)2]
Problem 71d
Sketch the structure of the complex in each of the following compounds and give the full compound name:
d. cis-[Ru(en)2Cl2]
- Complete the exercises below. Which complex ions in Exercise 23.71 have optical isomers?
Problem 72
Problem 73
The molecule dimethylphosphinoethane [(CH3)2PCH2CH2P(CH3)2, which is abbreviated dmpe] is used as a ligand for some complexes that serve as catalysts. A complex that contains this ligand is Mo(CO)4(dmpe) .
a. Draw the Lewis structure for dmpe, and compare it with ethylenediamine as a coordinating ligand.
b. What is the oxidation state of Mo in Na2[Mo(CN)2(CO)2(dmpe)] ?
c. Sketch the structure of the [Mo(CN)2(CO)2(dmpe)]2- ion, including all the possible isomers.
- Complete the exercises below. The square-planar complex [Pt(en) Cl₂] only forms in one of two possible geometric isomers. Which isomer is not observed: cis or trans?
Problem 74
Problem 77
Carbon monoxide, CO, is an important ligand in coordination chemistry. When CO is reacted with nickel metal, the product is [Ni(CO)4] which is a toxic, pale yellow liquid.
a. What is the oxidation number for nickel in this compound?
b. Given that [Ni(CO)4] is a diamagnetic molecule with a tetrahedral geometry, what is the electron configuration of nickel in this compound?
c. Write the name for [Ni(CO)4] using the nomenclature rules for coordination compounds.
- Complete the exercises below. Which of the following objects is chiral: a. a left shoe, b. a slice of bread, c. a wood screw, d. a molecular model of Zn(en)Cl₂, e. a typical golf club?
Problem 79
- Complete the exercises below. Solutions of [Co(NH₃)₆]²⁺, [Co(H₂O)₆]²⁺ (both octahedral), and [CoCl₄]²⁻ (tetrahedral) are colored. One is pink, one is blue, and one is yellow. Based on the spectrochemical series and remembering that the energy splitting in tetrahedral complexes is normally much less than that in octahedral ones, assign a color to each complex.
Problem 82
- Complete the exercises below. Given the colors observed for VO₄³⁻ (orthovanadate ion), CrO₄²⁻ (chromate ion), and MnO₄⁻ (permanganate ion) (see Exercise 23.84), what can you say about how the energy separation between the ligand orbitals and the empty d orbitals changes as a function of the oxidation state of the transition metal at the center of the tetrahedral anion?
Problem 85
- Complete the exercises below. When Alfred Werner was developing the field of coordination chemistry, it was argued by some that the optical activity he observed in the chiral complexes he had prepared was due to the presence of carbon atoms in the molecule. To disprove this argument, Werner synthesized a chiral complex of cobalt that had no carbon atoms in it, and he was able to resolve it into its enantiomers. Design a cobalt(III) complex that would be chiral if it could be synthesized and that contains no carbon atoms. (It may not be possible to synthesize the complex you design, but we will not worry about that for now.)
Problem 88
- Complete the exercises below. Generally speaking, for a given metal and ligand, the stability of a coordination compound is greater for the metal in the +3 oxidation state rather than in the +2 oxidation state (for metals that form stable +3 ions in the first place). Suggest an explanation, keeping in mind the Lewis acid–base nature of the metal–ligand bond.
Problem 89