Practice Questions

Critique the Valence Bond Theory by explaining two of its major limitations in describing the properties of coordination compounds.

Define the term 'ligand' in the context of coordination chemistry.

Recall the geometry of $[Ni(CO)_4]$ and $[PtCl_4]^{2-}$ complexes.

Why is geometrical isomerism not possible in tetrahedral complexes? Analyze the spatial arrangement of ligands.

Solve for the oxidation number of the central metal atom in the coordination entity $K_3[Cr(C_2O_4)_3]$.

Define the term 'coordination number' of a central metal ion.

Design a coordination compound that is expected to exhibit linkage isomerism and justify your choice of metal and ligand.

Evaluate the statement: 'Geometrical isomerism is impossible for tetrahedral complexes.' Justify your conclusion.

Describe homoleptic and heteroleptic complexes, providing one example for each.

Formulate the coordination isomer of $[ ext{Cr(NH}_3)_6][ ext{Co(CN)}_6]$ and justify why it is classified as such.

Analyze and explain why anhydrous copper sulphate ($CuSO_4$) is a white solid, whereas hydrated copper sulphate ($CuSO_4 \cdot 5H_2O$) is blue.

Apply IUPAC rules to provide the systematic name for the coordination compound $[Co(NH_3)_5(CO_3)]Cl$.

Analyze the M-C bond in metal carbonyls to explain the concept of synergic bonding.

Calculate the number of unpaired electrons in the octahedral complex ion $[Mn(CN)_6]^{3-}$.

Justify the diamagnetic nature of tetracarbonylnickel(0), $[ ext{Ni(CO)}_4]$, using Valence Bond Theory, considering that the ground state electronic configuration of Ni is $3d^8 4s^2$.

Compare the magnetic properties of $[NiCl_4]^{2-}$ (tetrahedral) and $[Ni(CN)_4]^{2-}$ (square planar) by applying the Valence Bond Theory.

Explain the difference between a double salt and a complex compound using one example for each.

Identify the central metal ion and its oxidation number in the coordination compound $K_3[Cr(C_2O_4)_3]$.

List the four main postulates of Werner's theory of coordination compounds.

Define an ambidentate ligand and give two examples.

Explain the terms 'coordination sphere' and 'counter ions' with reference to the complex $K_4[Fe(CN)_6]$.

A coordination compound has the formula $PtCl_4 \cdot 5NH_3$. When treated with excess $AgNO_3$, one mole of this compound precipitates three moles of $AgCl$. Analyze this observation to determine the structural formula of the complex and the secondary valence of platinum.

Apply IUPAC nomenclature rules to solve for the chemical formula of the compound Iron(III) hexacyanidoferrate(II).

Apply Crystal Field Theory to analyze why $[Fe(H_2O)_6]^{3+}$ is strongly paramagnetic, whereas $[Fe(CN)_6]^{3-}$ is weakly paramagnetic.

Contrast the chemical behavior of a double salt, like Mohr's salt $FeSO_4 \cdot (NH_4)_2SO_4 \cdot 6H_2O$, and a coordination compound, like potassium hexacyanidoferrate(II) $K_4[Fe(CN)_6]$, when dissolved in water.

Formulate the structures of all possible stereoisomers for the complex ion $[ ext{Co(en)}_2 ext{Cl}_2]^+$. Justify the existence of each isomer type.

Evaluate the relative thermodynamic stabilities of the complexes $[ ext{Ni(NH}_3)_6]^{2+}$ and $[ ext{Ni(en)}_3]^{2+}$. Justify your reasoning.

Propose a set of simple chemical tests to distinguish between the ionization isomers $[ ext{Co(NH}_3)_5 ext{SO}_4] ext{Br}$ and $[ ext{Co(NH}_3)_5 ext{Br}] ext{SO}_4$.

Propose a reliable method, other than X-ray crystallography, to distinguish between the cis and trans isomers of diamminedichloridoplatinum(II), $[ ext{Pt(NH}_3)_2 ext{Cl}_2]$.

Name the type of isomerism exhibited by the complex $[Co(NH_3)_5(NO_2)]Cl_2$.

Critique the foundational assumption of Crystal Field Theory that ligands are treated as point charges. Why is this a significant limitation?

Name a coordination compound used in the treatment of lead poisoning.

Justify, using Crystal Field Theory, why tetrahedral complexes rarely form low-spin configurations.

Propose a plausible structure for a complex containing Chromium(III), two ethane-1,2-diamine (en) ligands, and two thiocyanate ($ext{SCN}^-$) ligands. Create the systematic IUPAC name for this complex cation, assuming the thiocyanate binds through nitrogen.

Propose a detailed explanation for the observed color difference between an aqueous solution of $[ ext{CoF}_6]^{3-}$ and $[ ext{Co(CN)}_6]^{3-}$, using the principles of Crystal Field Theory.

Explain why geometrical isomerism is not possible in tetrahedral complexes.

Calculate the spin-only magnetic moment (in Bohr Magnetons) for the complex ion $[CoF_6]^{3-}$.

Recall the coordination number of the central metal ion in $[Pt(en)_2Cl_2]^{2+}$.

Examine the isomers $[Co(NH_3)_5Br]SO_4$ and $[Co(NH_3)_5SO_4]Br$. Analyze how you would experimentally demonstrate that they are ionisation isomers.

Examine the coordination entity $[Co(en)_2Cl_2]^+$ and demonstrate its geometrical and optical isomerism by drawing the structures of all possible isomers.

A solution of $[Ni(H_2O)_6]^{2+}$ is green, but a solution of $[Ni(CN)_4]^{2-}$ is colorless. Analyze this difference by applying Crystal Field Theory.

Design an experimental procedure to determine the formula of a cobalt(III) chloride-ammonia complex, given that its empirical formula is $ext{CoCl}_3 \cdot 5 ext{NH}_3$. Your procedure should allow you to distinguish between possible formulas like $[ ext{Co(NH}_3)_5 ext{Cl}] ext{Cl}_2$ and $[ ext{Co(NH}_3)_5( ext{H}_2 ext{O})] ext{Cl}_3$ (if dissolved in water).

Summarize the concept of the chelate effect.

Evaluate the magnetic properties of $[ ext{Fe(H}_2 ext{O)}_6]^{2+}$ and $[ ext{Fe(CN)}_6]^{4-}$. Calculate the theoretical spin-only magnetic moment for each and justify the difference based on ligand field strength.

Explain the concept of primary and secondary valences as proposed by Werner, using the example of $[Co(NH_3)_5Cl]Cl_2$.