Deck 8: Binding in Transition Metal Compounds and Coordination Complexes

Question 1

Which would you expect to have a lower melting temperature CrF₂ or CrF₅?

A) CrF₂
B) CrF₅
C) they will be approximately the same
D) they will be exactly the same

Answer 1

B

Question 2

What is the name of this compound, NbO₂?

A) Niobium (II) oxide
B) Niobium (III) oxide
C) Niobium (IV) oxide
D) Oxygen Niobate
E) Dioxygen Niobate

Answer 2

C

Question 3

The oxylate ion is a

A) monodentate ligand.
B) bidentate ligand.
C) tridentate ligand.
D) tetradentate ligand.
E) will not act as a metal ligand.

Answer 3

B

Question 4

What is the oxidation state of Cr in Cr(CO)₆?

A) 0
B) +1
C) +3
D) +6
E) -6

Question 5

What is the chemical formula of pentaamminechloroplatinum(IV) bromide?

A) [Pt(NH₃)₅Cl]Br
B) [Pt(NH₃)₅]ClBr
C) [Pt₅(NH₃)Cl]Br
D) [Pt(NH₃)₅Cl]Br₃
E) [Pt₂(NH₃)₅Cl]Br

Question 6

Name the following compound, Pt(H₂NCH₂CH₂NH₂)Cl₄]Cl₂

A) hexachloro(ethylenediamine)platinum (IV)
B) hexachloride(ethylenediamine)platinum (VI)
C) tetrachloro(ethylenediamine)platinum (IV) chloride
D) tetrachloro(ethylenediamine)platinum (VI) chloride
E) Platinum(ethylenediamine)hexachloride

Question 7

What is the chemical formula of potassium hexafluorocobaltate(III)?

A) [CoK]F₆
B) K[CoF₆]
C) K[CoF₆]₃
D) K₃[CoF₆]
E) K[Co₃F₆]

Question 8

Name the following compound, Na₂[NiCl₄].

A) disodium tetrachloronickel (II)
B) sodium tetrachloronickelate (II)
C) sodium tetrachloronickelate (IV)
D) sodium tetrachloronickel (II)
E) sodium nickel (II) chloride

Question 9

How many isomers are there of the triamminetriaquachromium (III) ion (octahedral)?

A) 1
B) 2
C) 3
D) 4
E) 6

Question 10

How many isomers are there of trisoxaltochromate (III) ion?

A) 1
B) 2
C) 3
D) 4
E) 6

Question 11

How many optical isomers are there for the square planar compound diaminedichloroplatinum (II)?

A) 0
B) 1
C) 2
D) 3
E) 4

Question 12

What can you say about the following two compounds?

A) they are isomers
B) they are enantiomers
C) they are isomers and enantiomers
D) they are the identical compounds

Question 13

A Zn²⁺ ion in a strong octahedral field will have how many unpaired electrons?

A) 0
B) 2
C) 3
D) 4
E) 8

Question 14

A Co²⁺ ion in a weak octahedral field will have how many unpaired electrons?

A) 0
B) 1
C) 2
D) 3
E) 7

Question 15

For a Mn²⁺ ion the number of unpaired electrons in an octahedral compound will be

A) greater in a weak field.
B) greater in a strong field.
C) the same in weak and strong fields.
D) will never have unpaired electrons.

Question 16

Which of the following statements is true for crystal field theory of an octahedral complex?

A) The d_xy, d_yz, d_xz orbitals are lower in energy than the d_z2, and the d_x2-y2 because they are unaffected by the ligand field.
B) The d_xy, d_yz, d_xz orbitals are lower in energy than the d_z2, and the d_x2- because their energy is increased less than the d_z2, and the d_x2-y2.
C) in low spin complexes the d_z2, and the d_x2-y2 are lower in energy than the d_xy, d_yz, d_xz orbitals.
D) a & c
E) b & c

Question 17

What is the crystal field stabilization energy for a high spin Co²⁺ octahedral complex?

A) 0
B) -(2/5)D_o
C) -(4/5)D_o
D) -(7/5)D_o
E) -(9/5)D_o

Question 18

The octahedral compound [FeCl₃(NH₃)₃] is found to be paramagnetic. This means

A) it must be a high spin complex.
B) it must be a low spin complex.
C) it could be either a high spin or low spin complex.
D) it has a crystal field stabilization that is zero.
E) a & d

Question 19

The octahedral complex [Co(H₂O)₆]³⁺ has an absorption at 549 nm. Based on this where do you think the absorption will be for [Co(NH₃)₆]³⁺ might be?

A) 590 nm
B) 437 nm
C) 549 nm
D) It won't have an absorption because it will be a high spin complex.
E) There is no way to predict.

Question 20

Compared to the [Co(NH₃)₄Cl₂]⁺ ion, the [Co(NH₃)₄(ox)]⁺ ion has an absorption that is farther to the blue. This means

A) the oxylate ion is a stronger field ligand than Cl^-.
B) the oxylate ion is a stronger field ligand than NH₃.
C) the oxylate ion is a weaker field ligand than Cl^-.
D) the oxylate ion is a weaker field ligand than NH₃.
E) both c & d

Question 21

[Co(H₂O)₆]³⁺ absorbs at 549 nm while [V(H₂O)₆]²⁺ absorbs at 806 nm.

A) D_o is larger for the Vanadium compound
B) D_o is smaller for the Vanadium compound
C) D_o is the same for the two compounds because they have the same ligands
D) there is no way to compare D_o for the two compounds from the data given

Question 22

Given that [Ni(NH₃)₆]²⁺ has an absorption at 926 nm and [Cr(NH₃)₆]³⁺ has an absorption at 463 nm, what is the ratio of D_o in the nickel compound compared to the chromium compound

A) D_o in the nickel compound is 2 times that of the chromium compound
B) D_o in the nickel compound is 0.5 times that of the chromium compound
C) D_o in the nickel compound is 4 times that of the chromium compound
D) D_o in the nickel compound is 0.25 times that of the chromium compound
E) D_o is the same as they have the same ligands

Question 23

[Cr(CN)₆]^3- absorbs at 376 nm. Given that D₀ in [Co(NH₃)₆]³⁺ is 1.23 time smaller than D₀ in [Co(CN)₆]^3-, where to you think the compound D₀ in [Co(NH₃)₆]³⁺ will absorb?

A) 253 nm
B) 278 nm
C) 311 nm
D) 452 nm
E) 463 nm

Question 24

Pt(NH₃)₂Cl₂ is a square planar complex. How many unpaired electrons does it have?

A) 0
B) 1
C) 2
D) 4
E) 8

Question 25

Generally speaking which is the least stable geometry for coordination complexes?

A) octahedral
B) square planar
C) tetrahedral
D) tetrahedral and octahedral are about the same and both less stable then square planar
E) square planer and octahedral are about the same and both less stable than tetrahedral

Question 26

In the VB picture what is the hybridization of the metal in an octahedral complex?

A) sp
B) sp²
C) sp³
D) dsp²
E) d²sp³

Question 27

Why are Zn²⁺ ions colorless in water?

A) they don't form coordination complexes with water.
B) the Zn²⁺/H₂O coordination complexes have filled d orbitals.
C) the Zn²⁺/H₂O coordination complexes are all paramagnetic.
D) the Zn²⁺/H₂O coordination complexes are all tetrahedral.
E) none of the above

Question 28

The vibrational frequency of CO when bound to a metal ion is lower than that of free CO because

A) the crystal field shifts the energy of the vibration.
B) CO is a weak field ligand.
C) the high electronegativity of the metal ion.
D) the metal donates an electron to a bonding orbital of CO.
E) the metal donates an electron to an antibonding orbital of CO.

Question 29

Would it be better to use Cr³⁺ or Fe³⁺ octahedral complexes when trying to determine if a ligand is a strong or weak field ligand?

A) Cr³⁺
B) Fe³⁺
C) either would be fine
D) neither would work

Question 30

[Cu(CF₃)₄]^- is found to be diamagnetic. What is its structure?

A) square planar
B) tetrahedral
C) either square planar or tetrahedral
D) octahedral (with two other water ligands)
E) it will be an unusual shape with a steric number of 8

Question 31

Using the Lewis classification of acids and bases, a hard base prefers to be attached to

A) a soft base
B) another hard base
C) a soft acid
D) a hard acid
E) a compound that exhibits "borderline" tendencies

Question 32

Which of the following best describes the lanthanide contraction?

A) f-orbitals are more directional than d-orbitals and therefore less effective at screening nuclear charge
B) f-orbitals are more diffuse than d-orbitals and therefore less effective at screening nuclear charge
C) the increase in atomic and ionic radii as one goes from left to right across the lanthanides
D) A and C
E) B and C

Question 33

The enthalpy of hydration for a metal ion is

A) equal to the energy associated with the hydration of the gas phase metal ion
B) equal to the ionization energy of the neutral metal atom
C) always positive
D) always negative
E) A and D