Postmetallocene lanthanide-hydrido chemistry:: A new family of complexes [{Ln{(Me3Si)2NC(NiPr)2}2(μ-H)}2] (Ln = Y, Nd, Sm, Gd, Yb) supported by guanidinate ligands -: Synthesis, structure, and catalytic activity in olefin polymerization

The new family of Lewis base free hydrido complexes of rareearth metals supported by guanidinate ligands [{Ln{(Me3Si)(2)NC(NiPr)(2)}(2)(mu H)}2] (Ln=Y, Nd, Sm, Gd, Yb) was synthesized and structurally characterized. Single-crystal X-ray and solution NMR studies revealed that these complexes are dimeric in both solid state and in [D-6]benzene. The dimeric hydrido complexes can adopt eclipsed (Nd, Sm, Gd) or staggered (Y, Yb, Lu) conformations depending on the metal atom size. Catalytic activity of these [{Ln{(Me3Si)(2)NC(NiPr)(2)}(2)(mu-H)}(2)] complexes in the polymerization of ethylene, propylene, and styrene has been investigated. Complexes of Sm and Y have high catalytic activity in ethylene polymerization (1268 and 442 gmmol(-1)atm(-1)h(-1), respectively).