Final Exam (100 Pts)

Chem.451 (Spring, 2005)

Final Exam (100 pts)

Name: ------, Student Clid #: ------, May 7, 2005

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(21 pts: 7 @ 3 pts). Please circle the ONE best answer:

Which of the following complexes one would expect to be labile?

a) [Co(NH3)5(NO2)]2+b) cis-Pt(NH3)2Cl2

c) [Cr(en)3]Cl2d) [Cr(CN)6]3-

Which of the following species does not obey the 18-e rule?

a) (η5-C5H5)Rh(η2-C2H4)(PMe3)b) [(η5-Cp)(CO)2Ru-Ru(η5-Cp)(CO)2]

c)HCo(CO)3d) [HFe(CO)4]-

3. What is the IUPAC name of the complex [Cu(NH3)4][PtCl4]

a) Tetraaminecopper(II)tetrachloroplatinate(IV)

b) Tetraaminecopper(II)tetrachloroplatinate(II)

c) Tetraaminecopper(II) tetrachloroplatinum(II)

d) Tetraaminocopper(II) tetrachloroplatinate(II)

What is the point group of cis-difluorotetraaminecobalt(III) ion?

a) D4h b) Td

c) C2vd) C2h

Consider the molecules and ions:

I) [CoCl4]2-II) SF4III) XeF4IV) Ni(CO)5

Which of these species belong to the point group C4v?

a) only II b) II and III

c) I, II and IIId) only IV

6. Which of the following species is expected to diamagnetic?

a) [V(H2O)6]2+b) [Fe(C2O4)3]4-

c) [CoCl4]2-d) [Fe(CN)6]3-

7. Arrange the following complex ions in order of decreasing ∆oct(largest ∆oct= 1smalles∆oct = 4):[CoF6]3-, [CoF6]4-, [Rh(H2O)6]3+ and [Rh(CN)6]3-

a) [Rh(H2O)6]3+> [Rh(CN)6]3- > [CoF6]3- > [CoF6]4-

b)[CoF6]4- > [CoF6]3-> [Rh(H2O)6]3+ > [Rh(CN)6]3-

c) [Rh(CN)6]3- [Rh(H2O)6]3+ > [CoF6]3- [CoF6]4-

d) [Rh(CN)6]3- [CoF6]3- > [Rh(H2O)6]3+ > [CoF6]4-

Part II.(26 pts) Coordination Chemistry

(4 pts) Write the structural formula for tetraamminechromium(III)-μ-amido-μ-hydroxo- bis(ethylenediamine)iron(III) sulfate

2. (4 pts) Sketch all possible geometrical isomers for [Co(C2O4)2Cl2]+ ion (C2O42- = oxalate ion), and then indicate which of these complexes would exhibit optical activity.

3. (18 pts) Rationalize for the following observations:

a) (5 pts) Diamagnetic compounds of cobalt(III) such as [Co(NH3)6]3+ and [Co(NO2)6]3- are orange-yellow. In contrast, the paramagnetic complexes [CoF6]3- and [Co(H2O)3F3] are blue.

b) (5 pts) The visible spectra of [Ni(NH3)6]2+ and [Ni(H2O)6]2+ give the same number of bands but at different positions (sketch a graph to explain your answer showing how many bands you expect to find).

c)(5 pts) A complex of nickel(II), [NiCl2(PPh3)2] is paramagnetic with a magnetic moment value μ = 2.96BM. The analogous complex of palladium(II) is diamagnetic (μ = 0). Include diagrams showing the molecular geometry and d-orbital energy levels for each complex ion as part of your answer

d) (3 pts) The color of trans-[Co(en)2Cl2]+ is less intense than that of cis-[Co(en)2Cl2]+.

Part III. (17 pts) Organometallic Compounds

(5 pts) Show the structural (show all bonds clearly) for (OC)3Fe(C8H8)Fe(CO)3, where C8H8 = cycloctatetraene.

2. (12 pts: 2 @ 6 pts each) Rationalize for 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 reaction of (η5-Cp)Fe(CO)2Br with Na[Co(CO)4] gave [(η5-Cp)(CO)Fe(μ-CO)2Co(CO)3] in which an Fe-Co bond does exist. Solely on the basis of the 18 e-rule explain your answer.

Part IV. (20 pts) Bioinorganic Chemistry:

(6 pts) The precise mechanism of cis-platin anticancer is uncertain. However, several possibilities have been identified that it includes blocking of DNA replication. Discuss one of these possible mechanisms.

2. (6 pts) Cis-platin shows several prominent side effects that include kidney and gastrointestinal problems and nausea. These arise as a result of the high dosage required and reactivity with a variety of other biomolecules including inhibition of enzymes.

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?

3. (8 pts)

a) Do you expect O2 to be a weak or strong ligand field?

b)Recall that deoxygenated myoglobin (Mb) is high spin, while MbO2 is low-spin. Is this consistent to part (a)? If not explain the inconsistency.

c)What prevents simple iron porphyrins from functioning as O2-carrier?

d) Briefly explain the role of the peptide portion of hemoglobin in preventing the irreversible oxidation of Fe2+?

______

Part V. (16 pts) Transition Metals:

(10 pts) Explain the following observations:

a)Aqueous solutions of Cr2+ are rapidly oxidized in air, as are solutions of Fe2+, though more slowly, whereas the aqueous solutions of the intervening ion, Mn2+ should be stable towards aerobic oxidation.

b) The uniformity in the properties of the lanthanides and the great diversity observed in the chemistry of actinides.

2. (6 pts) Predict the probable structure (bond order & electron configuration and magnetic properties) for the followingmetal-metal bonded tetragonal-prismatic complexes:

a) [Cr2(μ-O2CMe)4] b) [Rh2(μ-O2CMe)4(H2O)2]

You will have 140 minutes to complete this exam.

The exam has 9 pagesplus Periodic Table

When you are told to do so, tear off the Periodic Table cover sheet and use as required during exam.

1 / 1
H
1.01 / Periodic Table of the Elements / 2
He
4.00
2 / 3
Li
6.94 / 4
Be
9.01 / 5
B
10.81 / 6
C
12.01 / 7
N
14.01 / 8
O
16.00 / 9
F
19.00 / 10
Ne
20.18
3 / 11
Na
22.99 / 12
Mg
24.30 / 13
Al
26.98 / 14
Si
28.08 / 15
P
30.97 / 16
S
32.06 / 17
Cl
35.45 / 18
Ar
39.95
4 / 19
K
39.1 / 20
Ca
40.08 / 21
Sc
44.96 / 22
Ti
47.88 / 23
V
50.94 / 24
Cr
52.00 / 25
Mn
54.94 / 26
Fe
55.85 / 27
Co
58.93 / 28
Ni
58.69 / 29
Cu
63.55 / 30
Zn
65.38 / 31
Ga
69.72 / 32
Ge
72.59 / 33
As
74.92 / 34
Se
78.96 / 35
Br
79.90 / 36
Kr
83.80
5 / 37
Rb
85.47 / 38
Sr
87.62 / 39
Y
88.91 / 40
Zr
91.22 / 41
Nb
92.91 / 42
Mo
95.94 / 43
Tc
(98) / 44
Ru
101.1 / 45
Rh
102.9 / 46
Pd
106.4 / 47
Ag
107.9 / 48
Cd
112.4 / 49
In
114.8 / 50
Sn
118.7 / 51
Sb
121.8 / 52
Te
127.6 / 53
I
126.9 / 54
Xe
131.1
6 / 55
Cs
132.9 / 56
Ba
137.3 / 57
La
138.9 / 72
Hf
178.5 / 73
Ta
181.0 / 74
W
183.8 / 75
Re
186.2 / 76
Os
190.2 / 77
Ir
192.2 / 78
Pt
195.1 / 79
Au
197.0 / 80
Hg
200.6 / 81
Tl
204.4 / 82
Pb
207.2 / 83
Bi
209.0 / 84
Po
(209) / 85
At
(210) / 86
Rn
(222)
7 / 87
Fr
(223) / 88
Ra
226.0 / 89
Ac
227.0 / 104
Rf
(261) / 105
Db
(262) / 106
Sg
(263) / 107
Bh
(262) / 108
Hs
(265) / 109
Mt
(266) / 110
Uun
(269) / 111
Uuu
(272) / 112
Uub
(277)
58
Ce
140.1 / 59
Pr
140.9 / 60
Nd
144.2 / 61
Pm
(145) / 62
Sm
150.4 / 63
Eu
152.0 / 64
Gd
157.2 / 65
Tb
158.9 / 66
Dy
162.5 / 67
Ho
164.9 / 68
Er
167.3 / 69
Tm
168.9 / 70
Yb
173.0 / 71
Lu
175.0
90
Th
232.0 / 91
Pa
231.0 / 92
U
238.0 / 93
Np
237.0 / 94
Pu
(244) / 95
Am
(243) / 96
Cm
(247) / 97
Bk
(247) / 98
Cf
(251) / 99
Es
(252) / 100
Fm
(257) / 101
Md
(258) / 102
No
(259) / 103
Lr
(260)