This module is an introduction to the co-ordination and organometallic chemistry of 3d transition metals, and will encompass theory, physical methods and descriptive chemistry.

The aims of the module are:

• To outline the essential concepts in transition metal chemistry including: the valence shell, oxidation state and coordination number, ligands with hard and soft and donor atoms, structure and structural isomerism.
• To discuss formation of complex ions, and stability constants. The chelate effect.
• To outline crystal field theory and how it has developed to rationalise bonding in the d-block elements.
• To discuss the above in rationalizing the properties such as colour and magnetism, and reactivity (further formation of complex ions, ligand exchange and stability constants) of transition metal complexes
• To illustrate periodicity in the chemistry of the transition elements via a study of the Fe/Ru/Os group including:
• Discovery, isolation and technological importance of the elements and their compounds
• A survey of the chemistry of the different oxidation states and a comparison of the 3d elements with their heavier 4d and 5d relatives
• Brief comparisons/contrasts with neighbouring groups of elements.
• To introduce the chemistry, and some applications, of complexes in low oxidation states, including
• CO as an examplar of a π-acceptor ligand
• 3d Metal carbonyl complexes
• Analogous ligands, e.g. NO, RNC.
• The 18-electron rule; what it is, and when it applies to these complexes.

By the end of the module students should be able to

• Show an understanding of the key concepts and the application of these concepts in rationalizing the chemistry of the transition metals.
• Apply their knowledge of spectroscopic and physical techniques to work out the correct structure of a complex, given relevant chemical and spectroscopic information.
• Demonstrate an understanding of the social, economic and technological importance of selected transition elements
• Appreciate the significance of the syntheses, characterisation and chemistry of 3d metal complexes encountered in the practical module, CHEM245.
• Demonstrate an understanding of the application of the18-electron rule and the sort of complexes to which it applies.

Essential concepts in Transition Metal Chemistry - An Introduction

• Introduction to transition metal complexes. Coordination complexes and coordinate bonds. Oxidation state. Coordination number. Atomic d orbitals, dⁿ configuration.
• Ligands, hard and soft donors. Electroneutrality.
• Geometry, and isomerism.
• Formation of complexes in solution. Stability constants. The chelate effect.
• Crystal field theory. The basis of crystal field theory (CFT) for octahedral complexes. The origin of Δ. Factors affecting size of Δ. Colours in transition metal complexes; d-d transitions, selection rules. Charge transfer transitions.
• Magnetic properties. High-spin and low-spin complexes. Magnetic moment, spin-only formula.
• Crystal field stabilisation energy (C FSE). Favoured geometries, ionic radii, hydration enthalpies, latticed energies. Kinetic vs thermodynamic stability of complexes. Irving-Williams series.

Transition Metal Descriptive Chemistry

• Transition metal descriptive chemistry: Introduction. Trends across the d-block: oxidation state stabilities, with examples. Differences between 3d and 4d/5d elements.
• The chemistry of chromium, molybdenum and tungsten. Periodicity and trends within Group 6. Brief comparisons/contrasts with neighbouring groups of elements. 

Transition Metal Complexes Containing CO and other π-Acceptor Ligands

• Introduction to complexes of transition metals in low oxidation states. 18 electron rule, concept of synergistic bonding.
• Preparation, structure and bonding, chemical pro perties, reactivity and uses of:
• Binary metal carbonyls - preparation, characterisation, physical and chemical properties. Application of physical techniques (X-Ray crystallography, vibrational and NMR spectroscopies) for their characterisation.
• Substitution of CO by tertiary phosphine ligands - electronic and steric effects, and cone angle concept.
• Metal carbonyl anions, and hydrides
• Complexes containing CO analogues -nitric oxide (NO), isonitriles (RNC)

The course will be delivered in three blocks of 50-minute lectures, 10 describing essential concepts and bonding theories, 4 on 3d metal descriptive chemistry and 8 on low oxidation state chemistry, π-acceptor ligands and the 18-electron rule. These will be supported by three one-hour tutorials, and three two-hour workshop sessions.

Small group tutorials will involve discussion of problem sets, some of which contain past examination questions. Students will be expected to interact within the group to solve such problems, and are expected to lead discussions from time to time.

Workshops will consist of larger groups and will provide an opportunity for students to work through structured problem sets designed to aid students assimilation and understanding of the lecture material.

In addition, students will complete an extended essay on descriptive chemistry which will involve students in inde pendent learning.

In the formal examination, questions will be designed to test: (i) understanding of the bonding theories and their relevance for different types of complexes described in the course, (ii) understanding of the chemistry of the transition metals and involving the construction of competent arguments, (iii) problem-solving skills in assimilation of structural/spectroscopic data and its application to determining the identity and structure of various metal complexes, some of which have been encountered in the course, and some of which are variants of those encountered in the course.

Essential:

"Chemistry" C.E. Housecroft and E. C. Constable Prentice Hall, Harlow, 2002. ISBN (paperback) 130869244

Additional Sources

• D.F. Shriver and P.W. Atkins, "Inorganic Chemistry"(3 ^rd Edition), OUP Oxford  1999, ISBN (paperback) 0 19 850330 x.    (This comes with a CD-ROM containing many pictures used in the handouts for this course, together with other useful material.)
• "Advanced Inorganic Chemistry (Sixth Edition)" by F.A. Cotton, G.Wilkinson, C.A.Murillo and M. Bochmann (available in the Harold Cohen Library Undergrad collection).
• M.Bochmann's "Organometallics 1"is recommended for Dr.Whyman's lectures.  The latter makes a good introduction to "Organometallics 2" which is the coursebook for later year organometallic che mistry lectures.