Formation of a Paramagnetic Al Complex and Extrusion of Fe during the Reaction of (Diiminepyridine)Fe with AlR3 (R = Me, Et)

The reaction of the {2,6-[2,6-( i Pr)2PhNC(CH3)]2(C5H3N)}FeCl2 catalyst precursor with R3Al [R = Me, Et] afforded {2,6-[2,6-( i Pr)2PhNC(CH3)]2(C5H3N)}AlMe2 (1) and [η 4-LAl2Et3(μ-Cl)]Fe−(η 6-C7H8) (2), respectively. These paramagnetic species arises from both transmetalation, during which the strong terdentate ligand loses the Fe center, and reduction. The extent of reduction depends on the nature of the Al alkylating agent. The electrons necessary for the reduction are likely to be provided by cleavage of Fe−C bond of transient low-valent organo−Fe species.