Displacement Kinetics of η2-Bound Furan and 2,3-Dihydrofuran from Mn and Cr Centers: Evidence for the Partial Dearomatization of the Furan Ligand

• Published in: Inorganic chemistry Vol. 48; no. 16; pp. 7787 - 7793
• Main Authors: Andreatta, Jeremy R., Cieslinski, G. Benjamin, Batool, Madeeha, Sun, Xue-Zhong, George, Michael W., Brothers, Edward N., Darensbourg, Donald J., Bengali, Ashfaq A.
• Format: Journal Article
• Language: English
• Published: American Chemical Society 17.08.2009
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic900724f

The displacement of η2-coordinated ligands from the photolytically generated CpMn(CO)2L and BzCr(CO)2L [Cp = η5-C5H5, Bz = η6-C6H6, L = 2,3-dihydrofuran (DHF), furan] complexes by pyridine has been studied. The displacement reactions span a wide range of time scales from microseconds to hours and were studied using a range of time-resolved IR spectroscopic techniques. The substitution reactions follow a dissociative pathway and the measured activation enthalpies provide an estimate for the strength of the metal−(η2-furan) and metal−(η2-DHF) interactions. In these complexes, the Cr center binds both ligands weaker than the Mn center. There is a ∼6−10 kcal/mol difference in the binding enthalpies of η2-furan and η2-DHF to both metals suggesting that this difference is the result of a partial loss of resonance energy in the case of the aromatic furan ligand upon interaction with the metal.