Transition Metals and Coordination Chemistry

Report
Transition Metals and
Coordination Chemistry
Chapter 19
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Transition Metals and Coordination
Chemistry – Ch. 19
1. Define:
a. Lewis acid and Lewis base
b. Ligand
c. Chelate
d. Coordination number
e. Counter ion
f. Isomer
Transition Metals and Coordination
Chemistry – Ch. 19
2. Rank the following structural isomers by their conductivity in water.
[Cr(H2O)6]Cl3
[Cr(H2O)4Cl2]Cl•(H2O)2
[Cr(H2O)5Cl]Cl2•H2O
Transition Metals and Coordination
Chemistry – Ch. 19
3. Fill in the following table:
Name
Diamminedichloroethylendiaminechromium(III) sulfate
lithium hexahydroxoferrate(III)
Bis(ethylenediamine)oxalatomanganese(IV) nitrate
potassium dibromodicyanoplatinate(II)
Formula
Transition Metals and Coordination
Chemistry – Ch. 19
4. Fill in the following table:
Substance/Ion
[Pt(NH3)3Br]+
K[CoBrCl3(en)]
[Ni(CO)4] Br2
Na[Mn(C2O4)2(CN)(NO2)]
[Cu(NH3)4(H2O)2][PtI6]
Ox #
Coord. #
Name
Transition Metals and Coordination
Chemistry – Ch. 19
5. _____ isomers and _____ isomers are classes of
structural isomers.
a. Geometric, optical
b. Coordination, geometric
c. Linkage, geometric
d. Coordination, linkage
e. Geometric, linkage
Transition Metals and Coordination
Chemistry – Ch. 19
6. Which of the following complexes shows geometric
isomerism?
a. [Co(NH3)5Cl]SO4
b. [Co(NH3)6]Cl3
c. Li[Co(NH3)3Cl3]
d. K[Co(NH3)2Cl4]
e. Na3[CoCl6]
Transition Metals and Coordination
Chemistry – Ch. 19
7. Give the number of geometric isomers for the octahedral compound
[MA2B2C2], where A, B, and C represent ligands.
a. 1
b. 2
c. 3
d. 5
e. 6
Transition Metals and Coordination
Chemistry – Ch. 19
8. For the process Co(NH3)5Cl2+ + Cl–  Co(NH3)4Cl2+ + NH3, what
would be the ratio of cis to trans isomers in the product?
a. 1:1
b. 1:2
c. 1:4
d. 4:1
e. 2:1
Transition Metals and Coordination
Chemistry – Ch. 19
9. Which of the following statements about the complex ion Co(en)2Cl2+
is true? (en = ethylenediamine, NH2CH2CH2NH2)
a. The complex ion contains Co(I).
b. The complex ion exhibits cis and trans geometric isomers,
but no optical isomers.
c. The complex ion exhibits two geometric isomers (cis and
trans) and two optical isomers.
d. Because en is a strong field ligand (large Δ), the complex ion
is paramagnetic.
e. The geometric isomers of the complex ion have identical
chemical properties.
Transition Metals and Coordination
Chemistry – Ch. 19
10. The compound Co(NH3)4Cl3 (233.44g/mol) has several structural
isomers. A solution is made by dissolving 0.875 g of one of the
isomer in 25.0 g of water. The solution freezes at -0.56 °C. (Kf =
1.86 °C kg/mol)
Which of the following is the correct structural isomer?
a. [Co(NH3)4Cl3]
b. [Co(NH3)4Cl2]Cl
c. [Co(NH3)4Cl]Cl2
d. [Co(NH3)4]Cl3
Transition Metals and Coordination
Chemistry – Ch. 19
11. An orange complex and a violet complex were both found to have
ferric ion as their central metal; which one absorbs light with a
longer wavelength?
Transition Metals and Coordination
Chemistry – Ch. 19
12. Solutions of [Co(NH3)6]3+ , [Co(NO2)6]3-and [CoF6]3- are colored.
The solutions were red, yellow and blue. Match the solution to the
color.
Transition Metals and Coordination
Chemistry – Ch. 19
13. A crystal that contains a complex ion is known to absorb 266
kJ/mol. Determine the color of the crystal.
Color
λ (nm)
Violet
400
Blue
450
Blue-Green
490
Yellow-Green
570
Yellow
580
Orange
600
Red
650
Transition Metals and Coordination
Chemistry – Ch. 19
14. Draw the d orbital diagrams according to the crystal field model in
order to predict how many unpaired electrons are in each of the
following:
a. [Fe(CN)6]4b. [FeBr6]4c. [Mn(en)2]3+ (tetrahedral)
Transition Metals and Coordination
Chemistry – Ch. 19
Transition Metals and Coordination
Chemistry – Ch. 19
15. The complex ion [Zn(H2O)6]2+ is colorless whereas [Ni(H2O)6]2+ is
green, explain.
Transition Metals and Coordination
Chemistry – Ch. 19
1. Define:
a. Lewis acid => electron pair acceptor and Lewis base =>
electron pair donar
b. Ligand => Lewis base
c. Chelate => Ligand that can form more than one coordination
covalent bond
d. Coordination number => Number of coordination covalent
bonds per metal atom
e. Counter ion => Oppositely charged ion necessary to neutralize
another ion
f. Isomer => Same chemical formula – different properties
Transition Metals and Coordination
Chemistry – Ch. 19
2. Rank the following 1 M solutions of structural isomers by their
conductivity in water.
a. [Cr(H2O)6]Cl3  [Cr(H2O)6]3+ + 3Cl–
(4 ions)
b. [Cr(H2O)4Cl2]Cl•(H2O)2  [Cr(H2O)4Cl2]+ + Cl– + 2H2O
(2 ions)
c. [Cr(H2O)5Cl]Cl2•H2O  [Cr(H2O)5Cl]2+ + 2Cl– + H2O
(3 ions)
Relative conductivity => a > c > b
Transition Metals and Coordination
Chemistry – Ch. 19
3.
Name
Formula
lithium hexahydroxoferrate(III)
Li3[Fe(OH)6]
diamminedichloroethylendiaminechromium(III) sulfate
[Cr(NH3)2Cl2(en)] 2SO4
bis(ethylenediamine)oxalatomanganese(IV) nitrate
[Mn(en)2(ox)](NO3)2
or
[Mn(NH2CH2CH2NH2)2(C2O4)](NO3)2
potassium dibromodicyanoplatinate(II)
K2[PtBr2(CN)2]
Transition Metals and Coordination
Chemistry – Ch. 19
4.
Substance/Ion
Ox # CN
Name
[Pt(NH3)3Br]+
+2
4
triamminebromoplatinum(II) ion
K[CoBrCl3(en)]
+3
6
potassium bromotrichloro(ethylenediamine)cobalt(III)
[Ni(CO)4] Br2
+2
4
tetracarbonylnickel(II) bromide
Na2[Mn(C2O4)2(CN)(NO2)]
+4
6
sodium cyanonitrobisoxalatomanganate(IV)
[Cu(NH3)4(H2O)2][PtI6]
+2,
+4
6, 6
tetraamminediaquacopper(II) hexaiodoplatinate(IV)
Transition Metals and Coordination
Chemistry – Ch. 19
5. _____ isomers and _____ isomers are classes of structural isomers.
a. Geometric, optical
b. Coordination, geometric
c. Linkage, geometric
d. Coordination, linkage
e. Geometric, linkage
6. Which of the following complexes shows geometric isomerism?
a. [Co(NH3)5Cl]SO4
b. [Co(NH3)6]Cl3
c. Li[Co(NH3)3Cl3]
d. K[Co(NH3)2Cl4]
e. Na3[CoCl6]
Transition Metals and Coordination
Chemistry – Ch. 19
7. Give the number of geometric isomers for the octahedral compound
[MA2B2C2], where A, B, and C represent ligands.
a. 1
b. 2
c. 3
d. 5
e. 6
A
A
C
A
B
C
C
B
M
M
B
C
A
M
B
C
B
C
A
B
A
B
C
C
A
A
M
M
A
C
B
B
B
A
C
Transition Metals and Coordination
Chemistry – Ch. 19
8. For the process Co(NH3)5Cl2+ + Cl–  Co(NH3)4Cl2+ + NH3, what
would be the ratio of cis to trans isomers in the product?
a. 1:1
N
N
N
N
Cl
b. 1:2
N
Cl
N
Cl
Co
Co
Co
c. 1:4
Cl
N
N
N
N
N
d. 4:1
N
N
Cl
e. 2:1
N
N
N
Cl
Cl
Co
N
Cl
N
Co
N
Cl
Cl
Co
N
N
Cl
Cl
N
N
N
Transition Metals and Coordination
Chemistry – Ch. 19
9. Which of the following statements about the complex ion Co(en)2Cl2+
is true? (en = ethylenediamine, NH2CH2CH2NH2)
a. The complex ion contains Co(I).
b. The complex ion exhibits cis and trans geometric isomers,
but no optical isomers.
c. The complex ion exhibits two geometric isomers (cis and
trans) and two optical isomers.
d. Because en is a strong field ligand (large Δ), the complex ion
is paramagnetic.
e. The geometric isomers of the complex ion have identical
chemical properties.
Transition Metals and Coordination
Chemistry – Ch. 19
10. A solution is made by dissolving 0.875 g of Co(NH3)4Cl3 in 25.0 g
of water. The solution freezes at -0.56 °C. (Kf = 1.86 °C kg/mol)
Calculate the number of ions (i) produced when Co(NH3)4Cl3 is
dissolved in water.
ΔTf = - kfim
-0.56C = -(1.86 Ckg/mol)(i)(0.875g/233.44g/mol)/(0.025kg)
i = 2 => [Co(NH3)4Cl2]Cl
Transition Metals and Coordination
Chemistry – Ch. 19
11. An orange complex and a violet complex were both found to have
ferric ion as their central metal; which one absorbs light with a
longer wavelength?
The orange complex absorbs blue light and the violet complex
absorbs yellow light – λyellow > λblue – so the violet complex absorbs the
longer wavelength
Transition Metals and Coordination
Chemistry – Ch. 19
12. Draw the d orbital diagrams according to the crystal field model in
order to predict how many unpaired electrons are in each of the
following:
a. [ Fe(CN)6]4b. [CoBr6]3c. [Fe(H2O)4]3+ (tetrahedral)
Transition Metals and Coordination
Chemistry – Ch. 19
13. Solutions of [Co(NH3)6]3+ , [Co(NO2)6]3-and [CoF6]3- are colored.
The solutions were red, yellow and blue. Match the solution to the
color.
Color Seen
Color
Absorbed
Relative
Wavelength
Relative
Energy
Relative
Ligand
Strength
Ligand
red
green
medium
medium
medium
NH3
yellow
violet
shortest
highest
strongest
NO2-
blue
orange
longest
lowest
weakest
F-
Transition Metals and Coordination
Chemistry – Ch. 19
14. The complex ion [Zn(H2O)6]2+ is colorless whereas [Ni(H2O)6]2+ is
green, explain.
Zn2+ => [Ar]3d10 => since all of the d orbitals are filled the d
electrons if excited would have to absorb an energy outside of the
visible spectrum => if the compound doesn’t absorb visible light
it will be colorless (with the exception of black which is absorbing
all visible colors)

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