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Study guide

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Inorganic Chemistry III

Module 1

An introduction to Coordination Chemistry

CHI32T1

Dr N Vorster

None

Recommended reading:

BOOK

F.A. Cotton and G. Wilkinson, "Basic Inorganic Chemistry", 2nd Ed.

Butler and Harrod, "Inorganic Chemistry, Principles and Applications".

J.D. Lee, "Concise Inorganic Chemistry", 4th Ed.

 

CODE

CW

BH

L

 

Contents

General
Functions of this guide

General information and regulations

Course layout

Attendance
Tests and tutorials
Class mark
Examination
Pass requirements

Unit 1: Concepts in coordination chemistry

Lecture hours

Unit Content

Study Objectives

Unit 2: Bonding in coordination compounds
Lecture hours
Unit Content
Study Objectives

 

1. GENERAL

There is no single prescribed textbook and you will be provided with comprehensive notes on the relevant subject matter. However, you may consult the above list of reference books  for further information. Remember, what we do as lecturers will enable you to obtain your diploma; what you do will make you a chemist.

Reference books may be obtained from the library and/or from your lecturer.

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2. FUNCTIONS OF THIS GUIDE

To assist you in the interpretation of the syllabus

To break down the syllabus into smaller units

To highlight essential learning material

To enable you to evaluate your own progress

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3. GENERAL INFORMATION AND REGULATIONS

3.1 Course layout

The module "Introduction to Coordination Chemistry" is divided into two units, namely:

Unit 1 Concepts in Coordination Chemistry

Unit 2 Bonding in Coordination Compounds

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3.2 Attendance

You are strongly advised to attend all their lectures as failing to do so will affect the quality of work to be done in tutorials and the ability to answer questions in tests correctly.

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3.3 Tests and tutorials

You will write two (2) major class tests, each of 1.5 hours duration, to evaluate your understanding of the course content. In addition to these tests, you will complete tutorials on a weekly basis and write a number of short tutorial tests during the lecture periods. Dates for the class tests and minor tutorial tests will be announced during the lectures.

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3.4 Class mark

Class marks are determined from the marks obtained in the two class tests and the minor tutorial tests in the following ratio:

Class Test 1:

Class Test 2:

Minor tests: 

Class Mark: 

 331/3%

331/3%

331/3%

100%

Note that in order to obtain examination entrance, you must achieve a minimum of 40% for your class mark. See exam admission requirements. Also note the rules and regulations regarding writing and missing class tests in the Department’s Rules and Regulations Brochure.

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3.5 Examination

The final examination for this module will consist of one three (3) hour written examination. The paper will be divided into the following sections:

Section A: Concepts in Coordination Chemistry

Section B: Bonding in Coordination Compounds

Both sections must be answered. The mark allocation for each section in the examination paper is proportional to the number of lectures allocated to each section.

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3.6 Pass requirements

3.6.1 Modules

You will obtain a pass for a module if the combined class and examination mark is 50%, or more, provided that a subminimum of 40% has been obtained in the final examination. The combined mark for each module is computed as follows:

Class mark : 

Exam mark : 

Final mark : 

 40%

60%

100%

 

3.6.2 Course

The final course mark for Inorganic Chemistry III is calculated as a weighted average of the marks obtained for the individual modules, "Introduction to Coordination Chemistry", "Descriptive Chemistry of the Transition Elements" and "Practical Coordination Chemistry". Should you  fail one of the modules, you retain your pass mark for other modules passed. You will pass the course Inorganic Chemistry III only if a final mark of at least 50% is obtained for each module. See Calculating the final mark.

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4. UNIT 1 CONCEPTS IN COORDINATION CHEMISTRY

4.1 Lecture hours

6 × 2.25 hrs = 13.5 hrs

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4.2 Unit Content

4.2.1 Introduction 
4.2.2 Structures of coordination compounds 
4.2.3 Types of ligands

! classification i.t.o. charge 

! classification i.t.o. bonding 

4.2.4 Classification of metals

! the HSAB theory 

4.2.5 Isomerism in coordination compounds

! Geometrical isomerism

! Ionization isomerism

! Linkage isomerism

! Coordination isomerism

4.2.6 Nomenclature 
 
4.2.7 The stability of coordination compounds

! Equilibrium constants for complex formation 

! The chelate effect 

! Factors influencing the magnitude of the chelate effect

4.2.8 The reactivity of coordination compounds

! Substitution reactions of octahedral complexes 

! The trans effect

! Electron transfer reactions
CW 157
CW 158-162
 

BH 364-366

CW 164-165

 

CW 216-217

CW 165-169

 

 

 

 

CW 169-171
BH 368-371
 

CW 171-174

CW 174-176

 

 

CW 176-178

CW 190-193

CW 193-198

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4.3 Study Objectives

In this section, an overview is presented of the structures, nomenclature, reactivities, stabilities, and so on, of coordination compounds. These topics are important for later discussions on the theories of bonding of coordination compounds.

After completion of this unit you should be able to:

P explain what is meant by the terms "coordination compound", "coordination number", and "coordination geometry";

P for each of the coordination numbers two to six, mention the principal geometrical arrangement/s;

P classify typical ligands i.t.o. their bonding to metals;

P explain, with the aid of suitable examples, what is meant by the terms "type A-metal" and "type B-metal";

P write names for any coordination compound;

P write formulae for any coordination compound;

P explain, with suitable examples, what is meant by tetragonal, rhombic, and trigonal distortion of an octahedron;

P explain, with suitable examples, what is meant by the terms "geometrical isomerism", "ionization isomerism", "linkage isomerism", and "coordination isomerism";

P explain what is meant by "stepwise" and "overall" formation constants;

P express equilibrium relationships in terms of stability constants;

P calculate the stability constant for a given reaction under a given set of conditions;

P explain why there is generally a slowly descending progression in the values of the K’s in any particular system;

P interpret species distribution diagrams;

P explain what is meant by the terms "stable / unstable", "labile", and "inert";

P define the term "chelate effect";

P explain the operation of the chelate effect;

P discuss factors which influence the magnitude of the chelate effect;

P discuss the various mechanisms used to explain ligand replacement reactions;

P discuss the mechanisms used to explain electron transfer reactions;

P explain the term "trans-effect";

P use the trans-effect to rationalize certain synthetic procedures.

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5. UNIT 2 BONDING IN COORDINATION COMPOUNDS

5.1 Lecture hours

8 × 2.25 hrs = 18 hrs

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5.2 Unit Content
5.2.1 Introduction 
5.2.2 Valence bond theory 
5.2.3 Crystal/ligand field theory 

! The splitting of d-orbitals by electrostatic fields: 

- octahedral fields

- tetrahedral fields

- tetragonal distortions from octahedral symmetry

! Measurement of ) (10 Dq) 

! Factors influencing the magnitude of ) (10 Dq)

! d-Orbital occupations (magnetic properties): 

- octahedral complexes

- tetrahedral complexes

- square and tetragonally distorted octahedral complexes

- other forms of magnetic behaviour

! Structural and thermodynamic effects of d-orbital splittings: 

- ionic radii

- the Jahn-Teller effect

- hydration and lattice energies

- stabilization of oxidation states

- octahedral vs tetrahedral coordination

5.2.4 Molecular orbital theory 

! MO-diagram for octahedral complexes with no B-bonding

! Effect of B-bonding
L 202-203
L 203-204
CW 430-470

CW 430-435

 

 

 

CW 446-448

 

CW 439-446

 

 

 

 

CW 465-470

 

 

 

 

 

CW 435-439

 

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5.3 Study Objectives

In this section, the discussion on coordination compounds is continued. Theoretical treatments that will be presented include the valence bond theory, the electrostatic or crystal field model and the delocalized MO model. Each of these has its own advantages and disadvantages, and you should become comfortable with the language and approach of each of these theories.

After completion of this unit you should be able to:

P explain the general approach of the VB theory;

P use VBT to explain the occurrence of high-spin, outer-orbital complexes and low-spin, inner-orbital complexes;

P use VBT to predict geometrical shapes of coordination compounds;

P explain fully why and how a set of six negative charges, arranged octahedrally around a central metal ion, causes the set of d-orbitals to split;

P show, by starting with the energy level diagram for an octahedral field, that a square- planar field can be considered as an extreme case of tetragonal distortion;

P discuss (and use) the factors affecting the magnitude of );

P derive splitting diagrams for tetrahedral and trigonal-bipyramidal complexes;

P show, and explain, with the aid of simple energy level diagrams, which dn- systems are capable of giving both high- and low-spin configurations in octahedral fields;

P state the Jahn-Teller theorem;

P use the Cu2+ ion to show how the J.T. effect works;

P use CFT to explain the variation in radii for octahedral complexes;

P use CFT to explain the variation in the hydration energies of the divalent 3d-transition metals;

P explain why Fe3+ and Mn2+ exhibit different behaviours in terms of the stereochemistries and the spin states of the complexes they form, in spite of the similarity between their electronic configurations;

P predict, fully explaining the reasoning, which spinels will have the normal or inverted spinel structure;

P fully describe, with the aid of an energy level diagram, how a MO-diagram may be constructed for octahedral complexes in which there is no B-bonding (refer to Co(NH3)63+);

P indicate how B-bonding may affect the energies of electrons in a F-bonded system.

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