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Coordination Inorganic Chemistry
Practice Exam Coordination Chem
Name (last)________________(First)______________________
Read all questions before you start. Show all work and explain your answers to receive full credit. Report all numerical
answers to the proper number of significant figures. By signing your signature above you agree that you have worked alone and
neither give nor received help from any source. Keep your eyes on your own paper at all times
System
LENGTH:
VOLUME
MASS
Temperature
English:
1 ft = 12 in
1 gal = 4 qt
1 lb = 16 oz
T F = 1.8T C + 32
1 mile = 5280 ft
1 qt = 57.75 in3
1 ton = 2000 lb
1 yd = 3 ft
€
SI-
1 in = 2.54 cm
1 L = 1.057 qt
1 lb = 453.6 g
English:
1 mi = 1.609 km
1 qt = 0.946 L
1 oz = 28.35 g
Misc. info
1 mole = 6.02•1023
T C =
(T F − 32)
1.8
R = 8.314 J/ mol•K or .08206 L•atm/mol•K
€
Inorganic:
Spectrochemical Series:
I-< Br- < Cl- < NO3- < F- < CO32-< OH- < H2O < NH3 = en < phen < bpy < NO2-< SCN- < CN-< CO < ppy
f
Weak Strong
g
Color Wheel:
Bidentate Ligands
phen
11
bpy
ppy -
Multiple -choice. Show work for partial credit.
1
2
3
4
Which of the following chemicals is colorless?
a) [Ni(NH3)6]+
b) [Cu(en)2Cl2]
c) [Zn (OH)4]2-
d) None
Which of the following complexes has a coordination number of 6 ?
a) [Ag(NH3)2]+
b) [Co(en)2Cl2]+
c) [Zn (CO3)2]2-
d) None.
Which of the following complex ion solutions absorbs energy closer to the red end of the color spectrum?
a) [MI6]3b) [M(en)3]3+
c) [M(CN)6]3d) [M(bpy)3]3+
a) CO32-
Which is the only monodentate ligand ?
b) SCN-
c) EDTA
d) C2O42-
5
Which complex below is not a d6 specie?
a) Na2[Mn(EDTA)]
b) (NH4)3[RhCl6]
c) K4[Fe(C2O4)3]
d) [Ru(H2O)6](NO3)2
6
Which of the following chemicals has a metal with a +2 oxidation state?
a) [Ni(NH3)6] Cl3
7
8
Which complex below is the most paramagnetic?
a) [Ag(NH3)2] +
b) [Co(CO)6] PO4
Br
a)
10
c) [Zn (OH)4]2-
d) None
c) [Fe (CO3)3]4-
d) None are paramagnetic
Which compound below is capable of possessing geometric isomer?
F
9
b) K[Cu(en)2Cl2]
Pt
Br
F
F
F
b) F
Rh
Br
F
F
F
Cl
c)
S
F
What is the oxidation state of the mercury in[Zn(en)2][HgI4]
a) +1
b) +2
c) +4
F
F
C
d)
F
Br
F
d) Cannot be determine
Which is the likely structure for the compound, with a titanium +2 metal and iodine ligands?
a) Tetrahedral
b) Square planar
c) Octahedral
d) Not enough information
11
Name the following coordination, determine the coordination number, and determine whether it is
trigonal, tetrahedral, square planar, trigonal bipyramidal or octahedral.
i) Na[Co(C2O4)2(H2O)2]
Sodium diaquodioxalatocobaltate(III)
12
CN = 6, Octahedral
ii) [Co(H2O)5Cl]Cl2
Pentaaquochlorocobalt(III) chloride
CN = 6, Octahedral
iii) K[Al(CN)4]
Potassium tetracyanoaluminate
CN = 4, Tetrahedral
Define the following:
i) Isomers : Same chemical formula but different structural arrangement
ii) chelating agent: Ligand that bonds to metal at two sites
iii) dextrorotatory: Designation given to an optical isomer that rotates polarized light to the right.
13
Answer the following for the following questions for the structure shown.
The chemical formula is: CoH12O6Cl3
H
H
H
i) What ligand(s) are in the coordination sphere?
Water and chlorides that are shown inside the brackets
O
H
O
H
O
Co
O
H
Cl • 2H2O
H
Cl
ii) What are outside the coordination sphere?
Cl and two water shown outside the bracket
H
Cl
iii) How many d-electrons are on the central metal.
Cobalt (III), d6
14
Explain why atomic radii decrease very gradually from scandium to copper.
While the valence electrons remain in the same valence shell., Zeff becomes important going across the peiodic table.
15
Why do transition metals have more oxidation states than other elements?
Transition metals can lose electrons in their d-orbitals allowing them to have a range of oxdation state of +1 to +7.
16
(i) Which chemical between [CrF6]-4 and [W(F)6]-4 would you expect to have its spin pairing energy (PE) larger than
CF splitting energy, (Δ)? Explain.
[CrF6]-4 has SPE > CF splitting energy since Chromium is a smaller atom than tungsten and therefore would have a
smaller splitting energy.
ii) Which compound between [CrF6]-4 or [W(F)6]-4 would you expect to absorb longer wavelength of light ? Explain.
[CrF6]-4 will absorb longer wavelength of light (lower energy) since it has a smaller CF splitting energy.
(iii) [Cr(H2O)6]2+ is violet. Which ligand between CN- and Cl- will give a green CrL6 complex? Explain.
[CrCl6]-4 will display a green complex. The complement color of green is red, which is consistent with low energy light
absorb which correspond to small CF splitting..
(iv) Rank the following complex ions in order of decreasing Δ and energy of visible light absorbed? Explain your choice.
[Cr(CN)6]3[CoCl6]3[Cr(en)3]3+
Strong Field Ligand, large
Weak Field Ligand, small
Medium Field Ligand, medium
CF splitting
CF splitting
CF splitting
Δ
Energy of light
17
(1 Highest)
(3 – Lowest)
Highest Energy
(1 Highest)
Lowest Energy
(3 – Lowest)
(2-Medium)
Medium Energy
(2-Medium)
(15 pts) Name the following coordination compound, determine the coordination number, determine the number of delectrons and determine whether it is trigonal, tetrahedral, square planar, trigonal bipyramidal or octahedral.
i) Ni(C2O4)2(NH3)2
Diaminedioxalato Nickel(IV)
CN = 6,
d6,
Octahedral
ii) [Co(H2O)5Cl]Cl2
Pentaquachloro Cobalt(III) chloride
CN = 6,
d6,
Octahedral
iii) K2[Pt(CN)4]
Potassium tetracyano Platinate(II)
CN = 4,
d8,
Square Planar
18
(9pts) Complete the following statements for the complex ion
[Ni Cl (en)2 NH3] SO4
i) The oxidation number of Ni is
ii) The coordination number of Ni is __6__.
+3 .
iii) The name of the complex is ___.
Amine chloro bis(ethylenediamine) Nickel(III) sulfate
iv) Draw all possible isomers for the complex
Total of 3 isomers. One trans two cis, the cis are
enatiomer
Enatiomer Pair (Cis isomers)
19
Trans isomer
Using CFT, diagram the splitting pattern for the following complexes and then describe an experiment to determine
the following: (Be sure to describe the result of your experiment)
(i) Whether the cation in K2[Fe(CN)6] is a low-spin or a high-spin complex.
Here the iron is iron (IV) which means it is d(4) with 4 d-electrons. Since
iron is +4, then the splitting is large, and the molecule is most likely lowspin. This means that the molecule has two unpaired electrons. If the
molecules were to be high spin, it would have four unpaired electrons.
The experiment therefore to test for low-spin or high-spin is to test for
the degree of paramagnetism.
vs,
(ii) Whether nickel in K2[NiCl4] is square-planar or tetrahedral
In this complex, the Nickel is +2 or d(8). Almost all d(8) complexes with CN = 4 are square planar. Square planar
molecules will have splitting patterns of
vs
Test for degree of paramagnetism will determine if the complex is square planar or tetrahedral.
(iii) Whether a complex has the formula [Co(NH3)5Br]CO3 or [Co(NH3)5(CO3)]Br.
The complex, [Co(NH3)5Br]CO3, has coordination
The complex, [Co(NH3)5(CO3)]Br, has coordination
complex as a +2 cation. With the Br as a ligand. The
complex should have a small splitting relative to the other
complex. Treatment of this complex with silver nitrate
should show no free halogens.
complex as a +2 cation. With the CO3 as a ligand. The
complex should have a larger splitting relative to the
other complex. Treatment of this complex with silver
nitrate should show one free halogens.
20
There are four possible structures (A, B, C and D) for compounds with the general formula
[Fe(en)x (H2O)6-2x]SO4 where x = 0, 1, 2 or 3
Compounds A and C are paramagnetic and compounds B and D diamagnetic.
Compound B absorbs higher frequency light than compound D.
These complexes are highly colored ranging from yellow, orange violet, and green. Assume that the isomers with the
same chemical formula all have the same color.
Two of these do not have isomers. Compound B can exhibit only optical isomers. Compound D exhibit both optical
isomers and geometric isomers. (No coordination isomer is involve)
Answer the following questions concerning these four compounds.
i) Give the formula, chemical name and molar mass for compounds A, B, C and D.
ii) Draw the splitting pattern for compounds A, B, C and D with the d-orbitals labeled and the electrons filled.
iii) According to your diagram how many unpaired electron, if any, does each compound possess?
iv) Assign the color to each complex.
v) Draw the perspective diagram of all compounds (A, B, C and D) and their possible isomers.
A
[Fe(H2O)6]SO4
B
[Fe(en)3]SO4
C
[Fe(en)(H2O)4]SO4
D
[Fe(en)2(H2O)2]SO4
Absorb: Lowest Energy
(Red)
Absorb: Highest Energy
(Violet)
Reflect: See as Green
Reflect: See as Yellow
Absorb: Second Lowest
Energy (Orange or Yellow)
Reflect: See as Violet
Absorb: Second Highest
Energy (Blue or Green)
Reflect: See as Orange
HexaiaquoIron(II)
sulfate
MW = 259.9 g/mol
Tris(ethylenediamine)
Iron(II) sulfate
MW = 331.9 g/mol
EthylenediaminetetraaquoI
ron(II) sulfate
MW = 283.9 g/mol
Bis(ethylenediamine)diaquo
Iron(II) sulfate
MW = 307.9 g/mol