The mechanism and energetics of ligand (L) substitution (L = THF, cyclopentene, cyclohexene, cyclooctene) from photogenerated CpRu(CO)(X)L (X = Cl, I) complexes were studied using time-resolved infrared spectroscopy. The reactions proceed through a dissociative mechanism, and the Ru-L binding enthalpies were estimated. The trend in the bond enthalpies, Ru-(η 2-cyclooctene) ≈ Ru-(η 2-cyclopentene) > Ru-(η 2-cyclohexene), is correlated with the strain energy of the cycloalkene ring. For all ligands investigated, CpRu(CO)(Cl)-L binding enthalpies were lower than those for the analogous CpMn(CO) 2-L and BzCr(CO) 2-L complexes. DFT calculations indicate that the lower binding enthalpy for the Ru-L complexes is due to a greater reorganizational energy for the CpRu(CO)Cl fragment as it adopts a configuration suitable for interaction with the ligand.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry