Is the trinuclear complex the true reducingspecies in the Cp_2TiCl_2/Mn-and Cp_2TiCl_2/Zn-promoteed pinacol coupling?

摘要

Through a combination of kinetic,voltammetric andproduct analysis ,it has been found that a common Ti~III species obtained from the metal reduction of Cp_2TiCl-2 is involved in the electron transfer to benzaldehyde.A common species in the pinacl dimerization step was also demonstrated.In neither of the two steps is it necessary to invoke trinuclear complexes as previously proposed.