Chem. 451 (Spring, 2007)
Final Exam (105 pts)
Name: --------------------------------------------------------, Student Clid #: --------------------, May 11, 2007
LAST, First
Circle the alphabet segment of your Last Name: A-G
H-L
M-P
Q-Z
Please answer the following questions:
Part I: Multiple Choices (18 pts: 6 @ 3 pts). Please circle the ONE best answer:
1. Which of the following complexes one would expect to be labile?
I: K2[MnI6]
II: cis-Pt(NH3)2Cl2
III: K3[Fe(CN)6]
a) III and IV
b) I and III
c) Only IV
d) I and IV
IV: (NH4)2[Cr(O)Cl5]
2. Which of the following complexes are chiral?
I: [Ru(en)3]2-
II: [Pt(dien)Cl]+
III: cis-[Cr(C2O4)2Cl2]3-
a) Only III
b) II and IV
c) I and III
d) II and III
IV: trans-[Cr(C2O4)2Cl2]3-
3. Which of the following species belong to the point group C2v?
I: [CoCl2Br2]2-
II: [PdCl4]2-
III: trans-Pt(NH3)2Cl2
a) Only III
b) Only I
c) I and III
d) II and IV
IV: [NiBr4]2-
4. What is the point group of trans-difluorobis(ethylenediamine)cobalt(III) ion?
5.
6.
a) D4h
b) Td
c) C2v
d) Oh
Which of the following compounds is expected to be paramagnetic with a magnetic moment, μ
close to 3.9 BM?
a) K3[Fe(CN)6]
b) (NH4)2[Cr(O)Cl5]
c) K2[VCl4]
d) K2[MnI6]
On the basis of the 18-e rule, identify the most likely second row transition metal for the
complexes?
I: (η5-C5H5)M(η2-C2H4)(PMe3)
II: [(η5-Cp)(CO)2M-M(η5-Cp)(CO)2]
III: M(CO)(PMe3)2Cl (square planar)
IV: (η5-C5H5)2M(CO)2
a) Rh, Ru, Pd and Zr respectively.
b) Ru, Rh, Pd and Zr respectively.
c) Co, Fe, Ni and Ti respectively.
d) Rh, Ru, Pd and Mo respectively.
1
Part II. (34 pts) Coordination Chemistry
1. (14 pts) Explain the electron configuration in the following diamagnetic complexes
a) (7 pts) [Co(NH3)6]3+ on the basis of VBT, MOT and CFT (Include a diagram showing the
molecular geometry and d-orbital energy levels for the complex as part of your answer)
b) (3 pts) trans-[Co(NH3)4F2]+ on the basis of CFT (Include diagram showing the molecular
geometry and d-orbital energy levels for the complex as part of your answer)
2
c) (4 pts) [PdCl2(PPh3)2] on the basis of VBT and CFT (Include diagram showing the molecular
geometry and d-orbital energy levels for the complex as part of your answer)
2. (6 pts) Sketch all possible geometrical isomers and then indicate which of these complexes would
exhibit optical activity. Also identify each complex by name
a) [Fe(C2O4)2Cl2]+ ion (C2O42- = oxalate ion),
b) [PdCl2(PPh3)2] (diamagnetic)
3
3.
(14 pts) Rationalize for the following observations:
a) (6 pts) Solutions of the complexes [Co(NH3)6]3+, [Co(OH2)6]2- and [CoCl4]2- are colored. One
is pink, another is yellow-orange and the third is blue. Assign each color to one of the
complexes and explain the basis of your assignment.
b) (4 pts) [FeF6]3- is colorless whereas [CoF6]3- is colored and exhibits only a single band in the
visible region.
d) (4 pts) Solutions of [Cr(OH2)6]3+ are pale blue-green but the chromate ion CrO42- is an intense
yellow.
4
Part III. (18 pts) Organometallic Compounds
1. (6 pts) Determine the metal-metal bond order consistent with the 18-electron rule for the
following;
a) [(η5-C5H5)Mo(CO)3]2
b) [(η5-C5H5)Mo(CO)2]2
c) [(η5-C5H5)Mo(CO)]22-
2. (6 pts) Show how CH3CHO can be prepared by the oxidation of CH2=CH2 using [PdCl4]2- as a
catalyst by Wacker process.
5
3.
(6 pts) Rationalize the following observations:
a) On going from Fe(CO)5 to Fe(CO)3(PPh3)2, absorptions in the IR spectrum at 2025 cm-1 are
replaced by bands at 1944, 1886 and 1881 cm-1.
b) The complex ion [Co(CO)3(PPh3)2]+ has a single carbonyl stretching frequency whereas
Mo(CO)3(NC-C2H5)3 has two bands. Account for the structural changes.
Part IV. (18 pts) Bioinorganic Chemistry:
1. (10 pts) a) What prevents simple iron porphyrins from functioning as O2-carrier?
6
b) How these problem were overcome in synthesizing successful models for iron porphyrins
c) Briefly explain the role of the peptide portion of hemoglobin in preventing the irreversible
oxidation of Fe2+?
2. (6 pts) To counteract these effects, second generation of Pt-drugs, such as those shown above have
been developed that show similar therapeutic activities but at a lower dosages. What structure and
chemical characteristics of these molecules can be used to rationalize their enhanced therapeutic
properties?
_______________________________________________________________________________
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Part V. (18 pts) Transition Metals
1. (9 pts) Compare and contrast (similarities and dissimilarity) between the general properties of
transition metals, lanthanides and actinides.
8
2. (9 pts) Predict the probable structure (bond order & electron configuration and magnetic properties)
for the following metal-metal bonded tetragonal-prismatic complexes:
a) [Cu2(μ-O2CMe)4]
H3C
O
O
Mo
O
C
CH3
H3C
O
C
CH3
O
C
O
O O
O
Cr
Mo
?
C2H5
C
O
O
C
C2H5
C
O O
O
Cu
?
O
C
H3C
O
c) [Cr2(μO2CC2H5)4]
CH3
C
C
O O
O
H3C
CH3
C
Cu
b) [Mo2(μ-O2CMe)4]
O
?
C
C2 H5
cr
O
O
O
O
C
C2H5
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CHEM 451- Spring-2007
FINAL EXAM
You will have 140 minutes to complete this exam.
The exam has 9 pages plus Periodic Table
When you are told to do so, tear off the Periodic Table cover sheet and use as required during
exam.
Ligand abbreviations:
en = ethylenediamine, H2N-CH2CH2-NH2
dien = diethylenetriamine, H2N-CH2CH2-NH-CH2CH2-NH2
OX = oxalate dianion, -OOC-COO-
1
1
2
H
Periodic Table of the Elements
He
1.01
3
2
3
4
5
6
4.00
4
5
6
7
8
9
10
Li Be
B
C
N
O
F
Ne
6.94
9.01
10.81 12.01 14.01 16.00 19.00 20.18
11
12
13
14
15
16
17
Na Mg
Al Si
P
S
Cl Ar
22.99 24.30
26.98 28.08 30.97 32.06 35.45 39.95
21
19
20
K
Ca Sc Ti V
39.1
40.08 44.96 47.88 50.94 52.00 54.94 55.85 58.93 58.69 63.55 65.38 69.72 72.59 74.92 78.96 79.90 83.80
37
38
39
Rb Sr Y
22
40
23
41
24
25
26
27
28
29
30
31
32
33
34
35
18
36
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
42
43
44
45
46
47
48
49
50
51
52
53
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I
54
Xe
85.47 87.62 88.91 91.22 92.91 95.94 (98)
101.1 102.9 106.4 107.9 112.4 114.8 118.7 121.8 127.6 126.9 131.1
55
76
56
57
72
73
74
75
77
Cs Ba La Hf Ta W Re Os Ir
78
79
80
81
82
83
84
85
86
Pt Au Hg Tl Pb Bi Po At Rn
132.9 137.3 138.9 178.5 181.0 183.8 186.2 190.2 192.2 195.1 197.0 200.6 204.4 207.2 209.0 (209) (210) (222)
87
7
88
89
104 105 106 107 108 109 110 111 112
Fr Ra Ac Rf Db Sg Bh Hs Mt Uun Uuu Uub
(223) 226.0 227.0 (261) (262) (263) (262) (265) (266) (269) (272) (277)
58
59
60
61
62
63
64
65
66
67
68
69
70
71
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
140.1 140.9 144.2 (145) 150.4 152.0 157.2 158.9 162.5 164.9 167.3 168.9 173.0 175.0
90
91
92
Th Pa U
93
94
95
96
97
98
99
100 101 102 103
Np Pu Am Cm Bk Cf Es Fm Md No Lr
232.0 231.0 238.0 237.0 (244) (243) (247) (247) (251) (252) (257) (258) (259) (260)
10