23.3.2 Crystal Field Theory

Question 1

Carbon monoxide (CO) is a strong field ligand. What is the likely color of a solution of hexacarbonylcobalt(III) ion ( [Co(CO)6 ]3+ )?

Answer 1

yellow

Question 2

Which d orbitals are least affected by the ligands of a complex ion with square planar geometry?

Answer 2

dz2, dxz, and dyz

Question 3

Which of the following best defines high spin complexes?

Answer 3

complexes in which electrons remain unpaired and occupy as many d orbitals as possible

Question 4

According to the crystal field theory, why is fluoride (F − ) a weak field ligand, while ammonia (NH3 ) is a strong field ligand?

Answer 4

fluorine is more electronegative than nitrogen

Question 5

Which of the five d orbitals is lowest in energy when no ligands are present?

Answer 5

they are all equal in energy

Question 6

Which type of complex ion is more likely to be paramagnetic?

Answer 6

high spin

Question 7

Hexaamminecobalt(III) has a larger energy difference between the d orbitals than hexafluorocobaltate(III). Therefore, ammonia must be a _____ relative to fluoride.

Answer 7

strong field ligand

Question 8

Rank ammonia (NH3 ), fluoride ion (F − ), cyanide ion (CN − ), and water (H2O) in order from weakest field ligand to strongest field ligand.

Answer 8

F −, H2O, NH3, CN −

Question 9

The electron configuration of the iron(III) ion is [Ar] 3d5. How many unpaired electrons are in the d orbitals of iron(III) ion in an octahedral low spin complex?

Answer 9

1

Question 10

An octahedral low spin complex containing a transition metal with seven electrons in d orbitals is

Answer 10

paramagnetic