Chapter 5: Influence of Supramolecular Interactions on the Solid-state Photoreactivity of Metal Complexes

The current status of the solid state [2+2] photoreactivity of metal complexes has been presented in this chapter. Various supramolecular interactions have great influence in the design and ultimate reactivity of simple metal complexes, molecular rectangles, organometallic cages, clipping agents, zwitter ionic complexes, salts, etc. The formation of cyclobutane rings in this process can link metal complexes to yield dimers, oligomers or polymers, depending on the way the olefin pairs are aligned in the solid state. In several cases, where pedal motion is expected from criss-crossed olefin pairs to obtain the rctt-isomers, the photoreaction yielded unexpectedly rtct-isomers in the solid state. It has also been noted that some metal complexes pop like corns on hotplate during photochemical reactions under UV light. Many surprising mechanical behaviours, unpredicted phenyl-olefin dimerization, rare cycloreversion reactions and unexpected cyclobutane stereoisomers described here are the tip of an iceberg waiting to be discovered as routine phenomena in the photodimerization reactions of metal complexes in the future.