Group 3 (Sc, Y, Lu, La) benzyl complexes supported by a ferrocene diamide ligand are reactive toward aromatic N-heterocycles by mediating their coupling and, in a few cases, the cleavage of their C-N bonds. When these complexes reacted with 2,2′-bipyridine or isoquinoline, they facilitated the alkyl migration of the benzyl ligand onto the pyridine ring, a process accompanied by the dearomatization of the N-heterocycle. The products of the alkyl-transfer reactions act as hydrogen donors in the presence of aromatic N-heterocycles, ketones, and azobenzene. Experimental and computational studies suggest that the hydrogen transfer takes place through a concerted mechanism. An interesting disproportionation reaction of the dearomatized, alkyl-substituted isoquinoline complexes is also reported.

Group 3 η 2 -N,C-pyridyl complexes supported by a ferrocene-diamide ligand have been known to mediate the coupling of η 2 -N,C-pyridyl and coordinated-pyridine ligands with a concomitant dearomatization of the pyridine ligand. Examples reported previously by us were limited to a few cases. In order to investigate the scope of the coupling reaction, various η 2 -N,C-pyridyl scandium complexes were isolated and characterized. Their reactivity toward other aromatic N-heterocycles is presented along with the characterization of the subsequent reaction products. The coupling reaction is favored by ortho substitution, the presence of fused aromatic rings on the pyridine ligand, and chelating substrates. In one instance, the product of the coupling reaction between a scandium η 2 -N, C-pyridyl complex and 7,8-benzoquinoline could not be isolated because a subsequent isomerization reaction was favored. The coupling reaction is not restricted to η 2 -N,C-pyridyl fragments, and it proceeds also from CH 2 groups bound to the metal center and connected to a pyridine ligand. The reaction between η 2 -N,C-imidazolyl scandium complexes and 2,2 0 -bipyridine is also discussed.

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