The rate of photoisomerization of allyl alcohol to propanal catalyzed by iron pentacarbonyl (IPC) was monitored with 1H NMR in several solvents. A slower rate was observed in alcohols than in hydrocarbons or benzene. In addition, the isomerization's key p�allyl hydride intermediate was detected in only the hydrocarbons and benzene via FTIR spectroscopy. It has previously been shown that approximately 60-90% of iron pentacarbonyl (IPC) molecules form a weak, hexacoordinated complex with a single solvent molecule under ambient conditions in certain small alcohol and arene solvents. The close spatial proximity of the IPC and solvent molecules in the complex cause the preferential formation of a singly ethanol-substituted tetracarbonyl following UV excitation of an IPC-ethanol solution. Thus, the difference in rates is attributed to the formation of a singly alcohol-substituted tetracarbonyl side product, while the non-complexing hydrocarbons and benzene are not conducive to IPC ligand substitution.

Solvent dependent kinetics of the iron pentacarbonyl-catalyzed photoisomerization of allyl alcohol

243rd National Meeting (2012)

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