Nondissociative Mechanism for the Inversion of the Configuration in Cyclopentadienyl Di(aryloxo)titanium Complexes: An Entropy Discussion

Abstract:

Titanium complexes with two dioxo bridges between the Cp and the metal can be synthesized by the reaction of [Ti{η5-C5H3-1,3-(SiMe2Cl)2}Cl3] with different diols. Some of these complexes present a dynamic inversion process affording two diastereomers, A and B, which have been studied by X-ray diffraction and NMR techniques. The X-ray diffraction studies of [Ti{η5-C5H3-1,3-[SiMe2(κ1-1,2-O2C6H4)]2}X] X= Cl (2A), Me (4A), and Bn (5) complexes permit their absolute configuration to be assigned, and an epimerization mechanism has been supported by experimental evidence. Moreover, averaged activation energies (ΔH†, ΔG†) and entropies (ΔS†) for both the forward and reverse reactions were calculated from the Eyring-Polanyi equation from the NMR EXSY experiments; these are in agreement with the experimental evidence.

Año de publicación:

2017

Keywords:

Fuente:

scopus