Effect of M(CO)_3(M = Cr,Mn~+)on Aromatic C-Cl BDE in(eta~6-ArCl)M(CO)_3 Complexes

摘要

The coordination of Cr(CO)_3 to chlorobenzenes significantly reduces the C-Cl bond dissociation energy.Treatment of chloroarene-Cr(CO)_3 complexes with SmI_2/HMPA at room temperature led to complete dechlorination.Reaction of o-allyloxychlorobenzene-Cr(CO)_3 complexes with SmI_2 at room temperature resulted in the corresponding dechlorina-tive cyclization products in good to excellent yields.Competition experiments indicated the following relative reactivities of dehalogenation by SmI_2:PhI/PhCl-Cr(CO)_3/PhBr/ PhCl = 50:1:0.3:<0.001.On the other hand,the coordination of Mn(CO)_3~+ to chlorobenzene showed a much smaller activation effect.Density functional theory calculations revealed that the spin delocalization effect of the metal center plays an important role in the C-Cl bond activation.