Phenylene-Bridged Binuclear Organolanthanide Complexes as Catalysts for Intramolecular and Intermolecular Hydroamination

The phenylene-bridged bimetallic organolanthanide complexes p-bis{Cp '' Ln[N(SiHMe2)(2)](2)} phenylene (p-Ln(2); Ln = Y, La, Cp '' = tetramethylcyclopentadienyl) and m-bis{Cp '' La[N(SiHMe2)(2)](2)} phenylene (m-La-2) are investigated for possible Ln center dot center dot center dot Ln cooperative effects in hydroamination processes. These binuclear organolanthanide complexes efficiently catalyze the intramolecular hydroamination/cyclization of aminoalkenes, aminoalkynes, aminoallenes, and conjugated aminodienes with turnover frequencies as high as 10 h(-1) at 60 degrees C, as well as intermolecular hydroaminations with turnover frequencies as high as 0.4 h(-1) at 90 degrees C. Substrates include those having both compressed and extended junctures between the C-C unsaturation and the -NH2, group, as well as those with multiple -NH2 groups or places of C-C unsaturation. Reactivity trends appear to be dominated by nonbonded repulsive interactions, resulting in catalytic activities following the general trend m-Ln(2) < p-Ln(2). Organolanthanide amide complexes are also shown to catalyze the prototropic isomerization of alkynes.