FTIR spectroscopy was used to measure the extent of solvent-solute interactions of Fe(CO)5, and Os(CO)5 in halogenated benzene and cyclohexane solutions. It was determined that between 60 and 80 percent of M(CO)5 molecules from a complex with a single solvent molecule under ambient conditions. Os(CO)5 was found to complex to a greater extent than Fe(CO)5. The Gibbs free energy and the equilibrium constant for this reaction were found to range between -1.1 to -6.4kJ/mol and 1.6 to 6.0, respectively. The enthalpy of complexation was determined to be between -15 and-63 kJ/mol, while entropy varied between -35 and -106 J/mol * K. Peak shifting in the IR spectra and DFT-D calculations suggest that complexation can be driven by both electron donation to and withdrawal from the complexing halogen.

Solution dynamics of iron and osmium pentacarbonyl in halogenated solvents

251st National Meeting (2016)

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