Displacement kinetics of eta(2)-bound furan and 2,3-dihydrofuran from Mn and Cr centers: evidence for the partial dearomatization of the furan ligand.
The displacement of eta(2)-coordinated ligands from the photolytically generated CpMn(CO)(2)L and BzCr(CO)(2)L [Cp = eta(5)-C(5)H(5), Bz = eta(6)-C(6)H(6), 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-(eta(2)-furan) and metal-(eta(2)-DHF) interactions. In these complexes, the Cr center binds both ligands weaker than the Mn center. There is a approximately 6-10 kcal/mol difference in the binding enthalpies of eta(2)-furan and eta(2)-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.
Andreatta
Jeremy R
JR
Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA.
Cieslinski
G Benjamin
GB
Batool
Madeeha
M
Sun
Xue-Zhong
XZ
George
Michael W
MW
Brothers
Edward N
EN
Darensbourg
Donald J
DJ
Bengali
Ashfaq A
AA