Isomerism in metal complexes

Isomerism in Transition Metal Complexes

Ten Lower Sixth students attended a Gold CREST placement in the Chemistry Department at the University of Warwick. They spent one week investigating the ratio of fac and mer isomers in iron complexes. Many practical techniques were learnt, including refluxing and recrystallization. One of the most challenging elements was interpreting NMR (nuclear magnetic resonance) spectra and UV-Vis (ultra violet/visible) spectra. They were provided with excellent support by the Chemistry Department staff and technicians. A big ‘thank you’ goes to Professor Michael Ward, Dr Russ Kitson, Rob, Sam, Dani and Raj for this fantastic opportunity.

Here are some of the reflections from the students who attended the placement.

Ellie Aitchison said: ‘It was a thrilling opportunity to spend a week with the Chemistry Department at the University of Warwick, which offered us an introduction into the world of degree level chemistry. Throughout the week we were privileged to complete several experiments using complex compounds, and in some cases create new, previously unknown, samples. With the assistance of the team we were able to use and become familiar with advanced technology, such as infra-red and UV-Vis spectrometry, to analyse our products from each experiment. These reveal the different bonds and the overall structures of the samples. During the week the professors and researchers gave us detailed information on the transition metals, explaining complex mechanisms and energy level diagrams to help us with our understanding of the project. We managed to complete difficult and complex calculations from measurements collected in experiments and were given the independence to choose which compounds to use, making the whole process even more rewarding.

Charlotte Merry commented: ‘During the CREST project and placement, I learnt some useful techniques such as how to carry out my own NMR, IR and magnetic susceptibility investigations and I also further enhanced my scientific method. I really enjoyed the experiments and investigating what we made by carrying out the various tests. I found some of the calculations tough, but with the help of the researchers, Mr Kalsi and Dr Casey, I was able to complete all of the calculations myself by the end of the week.

The variations of experiments we did were amazing and in our group we made something that had never been made before! It was interesting to find out what we had actually produced and carry out experiments which had, most probably, never been done before. I found it fascinating to see how the experiments we did could be applied to real life and used in the manufacture of anti-cancer and anti-HIV drugs. The CREST project gives you a real insight into a different field and offers you the opportunity to be

able to work at undergraduate and sometimes graduate level alongside professionals in that field’.

Group members Kogulan, Viren, Siddhant and Sandeep reported the following:

‘During this placement, we learned the fundamentals of synthesising a transition metal complex and how this provides the basis for selfassembled co-ordination cages that can be used for drug delivery. This put into practice and reinforced some of our existing A Level Chemistry knowledge such as refluxing, Buchner filtration and preparation of a volumetric solution. As well as this, we were given the chance to acquire new analytical techniques such as nuclear magnetic resonance (NMR) spectroscopy and use state-ofthe-art equipment worth up to half a million pounds!

The experiment that we conducted was based upon a self-assembly template reaction. This means that the ligand (an ion or molecule that binds to a central metal atom) formed spontaneously at a metal ion. The reactants were mixed together in a round-bottomed flask fitted with a condenser and then refluxed on a hot plate. The product (complex) that we had formed was isolated using Buchner filtration and then dried.

Spectroscopic analysis of the complex was carried out after each experiment. This included an infra-red spectrum which identifies the functional groups present. Crucially we expected an imine functional group (C= N) to be present in all of our products and the results of the spectra did confirm this. Further tests included NMR and UV–Vis spectroscopic investigation of the samples. The opportunity to see these machines operate was a very beneficial experience and very much complemented the theory –it is difficult to fully appreciate a concept just from a textbook! Our main conclusion from this project was that this is a promising area of nanotechnology that has a lot of potential for future development. The nature of this project meant that we were making chemicals that were the first of their type in the world! Persistent and methodical trials and adjustments to the practical procedure could mean that one day we may create something that has far more worth than we first anticipate.

We would like to thank the academics at Warwick University for allowing us to use their world-class facilities and for providing excellent guidance and support throughout the placement. Many thanks also to our Chemistry teacher, Mr Kalsi, who arranged this placement. Without him we would not be enlightening you today with all this new science!’

Ellie Aitchison, U6th Student