UNIVERSITY OF LONDON
BSc and MSci DEGREES – August 2003, for Internal Students of the
Imperial College London
This paper is also taken for the relevant examination for the
Associateship
INORGANIC CHEMISTRY 1
RESIT
Tuesday 19th August 2003, 9.30 – 11.30
USE A SEPARATE ANSWER BOOK FOR EACH QUESTION.
WRITE YOUR CANDIDATE NUMBER ON EACH ANSWER
BOOK.
Inorg1RESIT/AUG2003 Turn over
Q1 Characterisation of Inorganic Compounds
Answer part (a) AND THREE of parts (b) to (f).
Information available for this question:
Assume 1H: I = ½, abundance = 100 %; 12C: I = 0, abundance = 100 %; 14N: I = 0, abundance = 100 %;
19
F: I = ½, abundance = 100 %; 31P: I = ½, abundance = 100 %; 35Cl: abundance = 75.5 %; 37Cl:
abundance = 24.5 %; 79Br: abundance = 50.5 %; 81Br: abundance = 49.5 %; 127I: abundance = 100 %.
(a) Answer BOTH parts.
H H
H
N C C H
H
H H
(i) Sketch the 1H NMR spectrum of the molecule above and explain the profile you have
presented.
(5 marks)
(ii) Explain the following IR stretching frequencies:
ν/ cm-1
1
H-35Cl 2991
1
H-37Cl 2988
2
H-35Cl 2145
(5 marks)
(b) Describe the intensities of colour that you would expect to observe in high spin octahedral
complexes of Fe3+ and Co3+. Explain your answer.
(5 marks)
(c) Sketch and label the 31P and 19F NMR spectra of the [PF6]− anion.
(5 marks)
(d) Sketch and label all of the vibrational modes of linear CO2 and non-linear H2O molecules.
Indicate which vibrational modes are IR active.
(5 marks)
(The question continues on the following page)
Inorg1RESIT/AUG2003 Page 1
(e) Explain the relative values of the following CO stretching frequencies
(M is a d-transition metal):
ν/ cm-1
CO 2143
M-CO 2200-1850
M 1850-1750
CO
M
M 1730-1620
M CO
M
(5 marks)
(f) Sketch the mass spectra of both BrCl and of ICl.
(5 marks)
Inorg1RESIT/AUG2003 Page 2
Q2 Periodicity and Inorganic Reactivity
Answer part (a) AND EITHER part (b) OR (c)
(a) Compare and contrast the structures, bonding and properties of the following forms of carbon:
diamond, carbon graphite and C60.
(13 marks)
(b) Describe what is meant by “the inert pair effect”, and explain its origin.
(12 marks)
(c) Compounds of the type MX3 in Group 15 are often electron pair donors. Why is this and what factors
enhance or weaken the effect?
(12 marks)
Inorg1RESIT/AUG2003 Page 3
Q3 Coordination Chemistry
Answer BOTH parts of this question.
(a) The complex of formula CoBr(NH3)5(SO4) exists as two isomers X and Y. When aqueous
barium chloride is added to X, a white precipitate is formed but no precipitate forms when
the test is repeated with Y. Conversely, the reaction between Y and silver nitrate solution
gives a cream precipitate, whilst no such precipitate forms with X. Identify X and Y, the
type of isomerism exhibited here, the number of d electrons in the metal's valence shell and
rationalise the observations.
(7 marks)
(b) With regard to transition metal coordination complexes, discuss TWO of the following
illustrating your answers with reference to relevant examples.
(i) The chelate effect. (9 marks)
(ii) Jahn-Teller distortion in copper(II) complexes. (9 marks)
(iii) Linkage isomerism and optical isomerism (9 marks)
Inorg1RESIT/AUG2003 Page 4
