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The Co2+ ion in aqueous solution is octahedrally coordinated and paramagnetic, with three unpaired electrons. Which one or ones of the following statements follow from this observation:
- Co(H2O)42+ is square planar
- Co(H2O)42+ is tetrahedral
- Co(H2O)62+ has a Δ0 that is larger than the electron-pairing energy;
- the d levels are split in energy and filled as follows: (t2g)5(eg)2
- the d levels are split in energy and filled as follows: (t2g)6(eg)1
The coordination compound potassium hexafluorochromate(III) is paramagnetic. What is the formula for this compound? What is the configuration of the Cr d electrons?
How many unpaired electrons are there in Cr3+, Cr2+, Mn2+, Fe2+, Co3+, Co2+ in
- a strong octahedral ligand field and
- a very weak octahedral field?
What is the d-orbital electronic configuration of Cr(NH3)63+? How many unpaired electrons are present? If six Br- groups were substituted for the six NH3 groups to give CrBr63-, would you expect Δ0 to increase or decrease?
For each of the following, sketch the d-orbita1 energy levels and the distribution of d electrons among them:
- Ni(CN)42- (square planar)
- Ti(H2O)62+ (octahedral)
- NiCl42- (tetrahedra1)
- CoF63- (high-spin complex)
- Co(NH3)63+ (low—spin complex)
Pt(II) can occur in the complex ion PtCl42-.
- What is the geometry of this ion? In the valence bond theory, what Pt orbitals are used in making bonds to the Cl- ions?
- What is the systematic name for the sodium salt of this ion?
- Using crystal field theory, draw the d-electron configuration for this ion. ls the ion paramagnetic or diamagnetic?
- Pt(II) can be oxidized to Pt(IV). Draw the d-electron configuration for the chloride complex ion of Pt(IV). Explain the difference between this configuration and that of Pt(II), Is the Pt(IV) chloride complex ion paramagnetic or diamagnetic?
A solution is prepared that is 0.025M in tetraamminecopper(II), Cu(NH3)42+. What will be the concentration of Cu2+ hydrated copper ion if the ammonia concentration is 0.10, 0.50, 1.00, and 3.00 M respectively? What ammonia concentration is needed to keep the Cu2+ concentration less than 10-15 M?
The ion Co(NH3)63+ is very stable, with Kf = 2.3 x 1034. If the hydrolysis constant for the ammonium ion, Kb, is 5 x 10-10, show that the equilibrium in the reaction
Co(NH3)63+ + 6H+ ↔ Co3+ + 6NH4+
lies far to the right. Then why does Co(NH3)63+ remain intact in hot concentrated sulfuric acid?
What is the solubility of Cu(OH)2 in pure water? In buffer at pH 6? Copper(II) forms a complex with NH3, Cu(NH3)42+, with Kf = 1.0 x 1012. What concentration of ammonia must be maintained in a solution to dissolve 0.10 mole of Cu(OH)2 per liter of solution?
Predict the electron configuration of an octahedral d4 complex with
- strong field ligands and
- weak field ligands, and state the number of unpaired electrons
Predict which of the following complexes absorbs light of the shorter wavelength and explain your reasoning: [Co(H2O)6]3+ or [Co(en)3]3+.
Compare the magnetic properties of [Fe(H2O)6]2+ and [Fe(CN)6]4-.
What change in magnetic properties (if any) can be expected when NO2- ligands in an octahedral complex are replaced by Cl- ligands in a d6 complex?
Draw the orbital splitting diagram for the following complex and give its electron configuration: tetrahedral CoCl42-.
The complex ion PdCl42- is diamagnetic. Propose a structure for PdCl42-.
Explain the following differences in color:
- For [Cr(H2O)6]Cl3 and [Cr(NH3)6]Cl3, one complex is violet while the other yellow Match the expected color with each complex and explain your identifications.
- For [Co(H2O)6]2+ and [CoCl4]2-, one complex is blue while the other reddish. Correlate a color with each complex and explain your identifications.
- One of the following solids is yellow, and the other is green: Fe(NO3)2·6H2O versus K4[Fe(CN)6·3H2O]. Indicate which is which and explain your reasoning.