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Our studies of molecular and materials chemistry have developed from a broader interest in the structure and bonding observed within a range of p-block (group 14-16) compounds which do not conform to conventional (i.e. 2 centre, 2 electron) bonding arguments. In many cases these compounds are ‘paramagnetic’ in solution, i.e. they possess one or more unpaired electrons and are therefore described as free radicals. In contrast many are often found to be ‘diamagnetic’ in the solid stateand have all their electrons paired.
We have examined the reactivity of these free radicals in solution, especially with transition metal organometallics and investigated whether modification to the chemical backbone leads to changes in their physical properties. The latter has led us to uncover both unexpected and remarkable behaviour; whilst these free radicals contain no metals, some exhibit magnetism at low temperature, a property more commonly associated with transition metals, their alloys and oxides. In other cases abrupt changes in their physical response are found on warming and cooling, offering potential to develop smart devices whose physical response (e.g. magnetic, conducting or optical) responds to external stimuli such as heat, light or pressure.
Samples of the sulfur-nitrogen radical C2S3N3 exhibit a memory of their thermal history between -50 oC and 40 oC.
Under-pinning these physical studies is a substantial body of synthetic work and this has required the implementation and/or development of generic synthetic methodologies to access these free radicals.