CHE3063 Organometallic Chemistry, Molecular Symmetry and Inorganic Electronics Coursework Questions 2021-22 Deadline: 7th December 2021 submit to SurreyLearn assignments folder Note that some of these questions are formative (F), meaning that you may complete them and ask for quick feedback from Dr Turner or Dr Riddlestone. The summative (S) questions will be used to determine your mark for this coursework. The following abbreviations are used Cy = cyclohexyl, Et = ethyl, Ph = phenyl, Me = methyl, bipy = 2,2'-bipyridine, Cp = cyclopentadienyl Formative Questions F1. Determine the metal valence electron count for each of the following compounds. (i) [(5-Cp)Rh(2-C2H4)(PMe3)] (ii) [TiCl2(5- Cp)] (iii) [(3-C3H5)2Rh(2-Cl)2Rh(3-C3H5)2] (iv) [Rh(Cl)(H)2(2-C2H4)(PPh3)2] (v) [Ir(H2)2(H)2(PCy3)]+ (vi) [(5- Cp)Co(Me)(PMe3)2]+ [Formative, Dr Turner] F2. Using symmetry arguments, show if and how vibrational spectroscopy can be used to distinguish between pure geometric isomers of [Cr(PMe3)4(CO)2]. Would you be able to recognise a mixture of isomers from vibrational spectroscopy? [Formative, Dr Turner] F3. The hydroformylation of 1-butene can be catalysed by [RhH(CO)(PPh3)3] and results in the formation of major and minor products. Draw the structures of both products and construct a catalytic cycle for the formation of the major product. Why are both linear and branched products both formed in this reaction? [Formative, Dr Riddlestone] Summative Questions S1. At 30°C the 1H-NMR spectrum of [Fe(CO)2(Cp)2] shows two peaks, one of which is at 5.6 ppm. At -55°C the spectrum shows 3 peaks at 4, 5.6 and 6.5 ppm with relative intensity 4:5:1, respectively. Further cooling results in the broad peak at 4 ppm splitting into two equally intense multiplets. Fully explain this data and sketch the structure of the compound. [6] S2. Explain all the factors that could affect the carbonyl stretching frequency in the generalized compound [MwLx(CO)y]z. M is a metal atom or ion; L represents non-carbonyl ligands; y is at least 1, w and x are positive integers, z is a positive or negative integer. [8] S3. The following table lists the vibrational bands for an isomer of N2F2. Band position (cm-1) infra-red spectrum Band position (cm-1) Raman spectrum 360 592 421 1010 989 1636 (i) Show how a simple calculation can determine the total number of vibrational bands. Fully explain the origin of the method that you use. [3] (ii) Which isomer of N2F2 is characterized by the data above? Explain a method to determine your answer without having to do any calculations. [3] (iii) For the isomer, chosen in part (ii), determine the irreducible representations for the normal vibrational modes. Determine which of the irreducible representations are observable in Raman and IR spectroscopies. Explain your reasoning. [9] (iv) One of the vibrations, listed in the table, is the s ...

1. CHE3063 Organometallic Chemistry, Molecular Symmetry and
Inorganic Electronics
Coursework Questions 2021-22
Deadline: 7th December 2021 submit to SurreyLearn
assignments folder
Note that some of these questions are formative (F), meaning
that you may complete them and ask
for quick feedback from Dr Turner or Dr Riddlestone. The
summative (S) questions will be used to
determine your mark for this coursework.
The following abbreviations are used
Cy = cyclohexyl, Et = ethyl, Ph = phenyl, Me = methyl, bipy =
2,2'-bipyridine, Cp = cyclopentadienyl
Formative Questions
F1. Determine the metal valence electron count for each of the
following compounds.
- -C2H4)(PMe3)]
- Cp)]
- - -C3H5)2]

2. -C2H4)(PPh3)2]
(v) [Ir(H2)2(H)2(PCy3)]+
- Cp)Co(Me)(PMe3)2]+
[Formative, Dr Turner]
F2. Using symmetry arguments, show if and how vibrational
spectroscopy can be used to
distinguish between pure geometric isomers of
[Cr(PMe3)4(CO)2]. Would you be able to
recognise a mixture of isomers from vibrational spectroscopy?
[Formative, Dr Turner]
F3. The hydroformylation of 1-butene can be catalysed by
[RhH(CO)(PPh3)3] and results in the
formation of major and minor products. Draw the structures of
both products and construct
a catalytic cycle for the formation of the major product. Why
are both linear and branched
products both formed in this reaction?
[Formative, Dr Riddlestone]
Summative Questions
S1. At 30°C the 1H-NMR spectrum of [Fe(CO)2(Cp)2] shows
two peaks, one of which is at 5.6
ppm. At -55°C the spectrum shows 3 peaks at 4, 5.6 and 6.5

3. ppm with relative intensity
4:5:1, respectively. Further cooling results in the broad peak at
4 ppm splitting into two
equally intense multiplets. Fully explain this data and sketch
the structure of the compound.
[6]
S2. Explain all the factors that could affect the carbonyl
stretching frequency in the generalized
compound [MwLx(CO)y]z. M is a metal atom or ion; L
represents non-carbonyl ligands; y is at
least 1, w and x are positive integers, z is a positive or negative
integer.
[8]
S3. The following table lists the vibrational bands for an isomer
of N2F2.
Band position (cm-1)
infra-red spectrum
Band position (cm-1)
Raman spectrum
360 592
421 1010
989 1636
(i) Show how a simple calculation can determine the total

4. number of vibrational bands.
Fully explain the origin of the method that you use.
[3]
(ii) Which isomer of N2F2 is characterized by the data above?
Explain a method to
determine your answer without having to do any calculations.
[3]
(iii) For the isomer, chosen in part (ii), determine the
irreducible representations for the
normal vibrational modes. Determine which of the irreducible
representations are
observable in Raman and IR spectroscopies. Explain your
reasoning.
[9]
(iv) One of the vibrations, listed in the table, is the symme tric
stretching of the bond
between two nitrogen atoms. Which one of the frequencies can
be assigned to this
mode, and why?
[2]
S4. A simulated IR spectrum of [Rh(CO)3] is shown below. Use
this data to deduce the geometry
of the Rh complex that was used in the simulation. Fully justify
your answer.
[6]

5. S5. The IR spectra (below) are of two complexes, each with
stoichiometry [M2(CO)x] (M = a first-
row transition metal, x = an integer). Both compounds retain the
same structures in solution
and the solid state. Determine the possible identity of M and x
for samples A and B. Fully
explain your reasoning.
[4]
S6. Explain / rationalize the following statements:
(i) A researcher experimentally determines the Tolman cone
angles for PPh3 and
P(MeC6H4)3 to be identical. However, a different researcher
determines the
angles to be different.
[3]
(ii) [Fe(CO)5] has bands in its IR spectrum at 2025 and 2000
cm-1 but has only one peak
in the 13C-NMR. When [Fe(CO)5] is reacted with PPh3 under
UV radiation the IR peaks
are replaced by a single IR band at 1885 cm-1.
[5]
(iii) The reaction of PtCl2 and two equivalents of CO at high

6. pressure and temperature
gives a mixture of isomers. These isomers have different Pt-C
and C-O bond lengths.
Which of the isomers has the longer or shorter of each of these
bond lengths.
Explain your answer.
[6]
S7. The reaction between [Fe(CO)5] and Na2[Fe(CO)4] in THF
evolves CO gas and gives a salt (A)
with a 2:1 ratio of Na to anion. The Raman spectrum of the
product has a low frequency
absorption at 160 cm-1. Looking at both Raman and IR spectra,
the bands attributed to CO
stretching are all are around 2100 cm-1. Suggest a structure for
the anion of salt A and show
how it agrees with the spectroscopic evidence.
[4]
S8. The cationic rhodium complex [Rh(NBD)(PPh3)2]+ (NBD =
norbornadiene) reacts with excess
dihydrogen in the coordinating solvent EtOH to give a metal
complex A and an organic
molecule B.
(i) Draw the structures of [Rh(NBD)(PPh3)2]+, complex A and
the organic product B.

7. [5]
[Rh(NBD)(PPh3)2]
+
excess H2
EtOH
A B+
(ii) It is possible for complex A to exist as different isomers.
How could the specific
isomer formed in the reaction be identified and characterised?
[3]
(iii) A THF solution of complex A is an efficient catalyst for
the hydrogenation of the
terminal alkene 1-hexene. However, if PPh3 is added to the
reaction mixture or if the
reaction solvent is changed to acetonitrile (MeCN) no catalytic
hydrogenation is
observed. How can these observations be rationalised?
[5]
S9. State whether you would expect each of the four following
transition metal alkyl complexes

8. to be stable? Explain your reasoning.
[CpFe(PPh3)(CO)Et] [Pd(PCy3)2(Et)Br]
[Ir(PMe3)3(Et)Br2] [Fe(bipy)2(Et)2]
[4]
S10. The complexes [Ir(PPh3)2(CO)Cl] and [Ru(dppe)2H]+
both react with dihydrogen to form
complexes A and B respectively, shown below.
(i) Draw the structures of A and B and indicate how the
oxidation states of Ir and Ru
change upon reaction with dihydrogen.
[4]
(ii) Explain how the products A and B differ with regards to
their progression along the
oxidative addition pathway and rationalise this difference in
reactivity between the
two complexes.
[8]
S11. Homogeneous catalysis can be understood at the molecular
level. Using relevant examples
explain how this understanding can be used to improve and
optimise a catalyst. (max 1 page

9. font size 12 single spaced, references must be included but do
not count in the page limit).
[10]