Hydrido Complexes of Yttrium and Lutetium Supported by Bulky Guanidinato Ligands [Ln(μ‐H){(Me 3 Si) 2 NC(NCy) 2 } 2 ] 2 (Ln = Y, Lu): Synthesis, Structure, and Reactivity

Lewis base free hydrido complexes of yttrium and lutetium supported by bulky cyclohexyl‐substituted guanidinato ligands, [Ln(μ‐H){(Me 3 Si) 2 NC(NCy) 2 } 2 ] 2 (Ln = Y, Lu), were synthesized and characterized. Single‐crystal X‐ray diffraction studies revealed dimeric structures. 1 H NMR spectroscopy shows that complex [Y(μ‐H){(Me 3 Si) 2 NC(NCy) 2 } 2 ] 2 retains its dimeric structure in C 6 D 6 solution. Scrambling of the hydrido complexes [Ln(μ‐H){(Me 3 Si) 2 NC(NCy) 2 } 2 ] 2 (Ln = Y, Lu) in C 6 D 6 resulted in an equilibrium mixture containing the heterodimetallic species [{(Me 3 Si) 2 NC(NCy) 2 } 2 Y(μ‐H) 2 Lu{(Me 3 Si) 2 NC(NCy) 2 } 2 ], indicating the dissociation of dimers and the presence of monomeric species in solution. Both compounds initiate the polymerization of ethylene: the activity of the cyclohexyl‐substituted yttrium complex, [Y(μ‐H){(Me 3 Si) 2 NC(NCy) 2 } 2 ] 2 , is much lower than that of the isopropyl‐substituted analogue, [Y(μ‐H){(Me 3 Si) 2 NC(N i Pr) 2 } 2 ] 2 , while in the case of lutetium the activities of [Ln(μ‐H){(Me 3 Si) 2 NC(NR) 2 } 2 ] 2 (R = i Pr, Cy) are similar. Complexes [Ln(μ‐H){(Me 3 Si) 2 NC(NR) 2 } 2 ] 2 (Ln = Y, Lu; R = i Pr, Cy) were shown to catalyze efficiently the hydrosilylation of 1‐nonene with PhSiH 3 (at a 1:1 substrates mol ratio) to give the terminal silane PhSiH 2 ( n ‐C 9 H 19 ) exclusively. If the hydrosilylation reaction is carried out in the presence of a twofold molar excess of 1‐nonene, double addition takes place and leads to the formation of tertiary silane PhSiH( n ‐C 9 H 19 ) 2 , which was obtained in 96 % yield. The hydrido complexes [Ln(μ‐H){(Me 3 Si) 2 NC(N i Pr) 2 } 2 ] 2 (Ln = Y, Lu) efficiently initiate the ring‐opening polymerization of ϵ‐caprolactone to give polymers with molar mass up to 80000.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)