Chapter 21 Multiple Choice Questions

. A reaction sequence in which an intermediate of reduced coordination number is formed by the departure of the leaving group is called:

an associative mechanism

a dissociative mechanism

an interchange mechanism

. How can one obtain the nucleophilic discrimination factor S (i.e. a measure of the responsiveness of a square planar complex to the nucleophilicity) for the entering group?

by calculating the R² of the log k₂(Y) versus the n_Pt(Y) line

by calculating the y-axis intercept of the log k₂(Y) versus the n_Pt(Y) line

by calculating the slope of the log k₂(Y) versus the n_Pt(Y) line

. The rate-determining step in octahedral complex substitution is believed to be:

an associative step

a dissociative step

an interchange step

. Find the correct statement:

Octahedral substitution reactions that go through a square-pyramidal intermediate result in the retention of the original geometry. A trigonal-bipyramidal intermediate may lead to isomerization.

Octahedral substitution reactions that go through a square-pyramidal intermediate do not retain the original geometry. A trigonal-bipyramidal intermediate may lead to isomerization.

Octahedral substitution reactions that go through a trigonal-bipyramidal intermediate result in the retention of the original geometry. A square-pyramidal intermediate may lead to isomerization.

. Inner-sphere and outer-sphere redox mechanisms are different in that:

The inner-sphere mechanism involves simple electron transfers, while the outer-sphere mechanism involves atom transfers. The inner-sphere mechanism forms a bridged transition state involving the reactants' coordination spheres, while the outer-sphere one does not.

The inner-sphere mechanism involves atom transfers, while the outer-sphere mechanism involves simple electron transfers. The outer-sphere mechanism forms a bridged transition state involving the reactants' coordination spheres, while the inner-sphere one does not.

The inner-sphere mechanism involves atom transfers, while the outer-sphere mechanism involves simple electron transfers. The inner-sphere mechanism forms a bridged transition state involving the reactants' coordination spheres, while the outer-sphere one does not.

. Usually, photosubstitution and photoisomerism are associated with:

exclusively photooxidation reactions

d–d transitions only

d–d transitions and photooxidation reactions with charge-transfer transitions

. Which statement is correct?

Populating metal–metal antibonding orbitals with electrons can sometimes initiate photodissociation.

Populating metal–metal bonding orbitals with electrons can sometimes initiate photodissociation.

Populating metal–ligand bonding orbitals with electrons can sometimes initiate photodissociation.

. Find mechanisms that are used to explain the isomerization of octahedral complexes with chelating ligands.

The Berry pseudorotation mechanism

The Bailar twist and Ray-Dutt twist mechanisms

The Thompson mechanism

. In which of the following cases one should consider the base hydrolysis as a predominant mechanism?

Any time the solution contains high concentration of OH^– ions.

In the cases when hydroxyl groups (OH^–) are coordinated on the metal and the concentration of H₃O⁺ions is high in the solution.

In the cases when the acidic hydrogens are present on the ligands (for example coordinated NH₃) and OH^– ions are present in the solution.

. Find the correct statement:

Steric crowding disfavours associative mechanisms.

Since the octahedral complexes follow dissociative mechanism, the nature of the leaving group never influences the substitution rate.

The Eigen–Wilkins mechanism explains the substitution reactions in the square-planar complexes.

Chapter 21 Multiple Choice Questions

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