Lanthanide-mediated ligand transfer reactions--a route to late transition metal bisamido complexes.

The reaction of [{O(SiMe2Ap)2}2LnLi(thf)n] 1 (Ln=Nd, n=2) and 2 (Ln=La, n=3) in hexane with [(dme)NiCl2] (dme=dimethoxyethane) and [(cod)PtCl2] (cod=1,5-cyclooctadiene) leads to the dimeric Ni complex [{O(SiMe2Ap)2}2Ni2] (3) and the mononuclear platinum compound [O(SiMe2Ap)2Pt] (4), respectively (O(SiMe2ApH)2=bis(4-methyl-2-pyridylamino)tetramethyldisiloxane). Compounds 3 and 4 have been characterized by X-ray crystal structure analysis. The ligand-transfer reactions probably proceed via heterobimetallic intermediates. A model complex of such an intermediate [{O(SiMe2Ap)2}2NdPdMe] (7) was isolated by reacting 1 with [(cod)PdMeCl]. Applications of complex 3 in ethylene oligomerization were investigated. Highly branched oligomers with a very narrow molecular weight distribution (Mn=230 g mol−1 (relative to polystyrene standards), Mw/Mn=1.14) are produced when Et3Al2Cl3 is employed as a co-catalyst and CH2Cl2 as the solvent (TOF=122 000 h−1). Treatment of one equivalent of 1 or 2 with two equivalents of [(cod)CuCl] results in the formation of the polycyclic tetranuclear complex [{O(SiMe2Ap)2}2Cu4] (8). An X-ray crystal structure analysis of 8 shows channels formed by a series of fourteen-membered rings in the solid state.