Yttrium and Lithium Keto-β-Diketiminate Complexes [{2,6-Me2C6H3N=C(Me)}2CС(tert-Bu)=O]2Y(μ2-Cl)2Li(THF)2 and {[{2,6-Me2C6H3N=C(Me)}2CС(tert-Bu)=O]Li(THF)}n. Synthesis, Molecular Structures, and Catalytic Activity in ε-Caprolactone Polymerization

Abstract The reaction of lithium β-diketiminate [{2,6-Me 2 C 6 H 3 N=CMe} 2 CH]Li with benzophenone in toluene at 25°C affords the coordination complex [{2,6-Me 2 C 6 H 3 N=CMe} 2 CH]Li(Ph 2 C=O) ( I ). New keto-β-diketimine {2,6-Me 2 C 6 H 3 N=C(Me)} 2 CHC( tert -Bu)=O ( II ) is synthesized by the reaction of tert -Bu(C=O)Cl with [{2,6-Me 2 C 6 H 3 N=CMe} 2 CH]Li. The metallation of keto-β-diketimine II with n -butyllithium in THF at 0°C gives lithium keto-β-diketiminate {[{2,6-Me 2 C 6 H 3 N=C(Me)} 2 CС( tert -Bu)=O]Li(THF)} n ( III ). The exchange reaction of YCl 3 with compound III (molar ratio 1 : 2, THF) affords the yttrium bis(keto-diketiminate) complex [{2,6-Me 2 C 6 H 3 N=C(Me)} 2 CС( tert -Bu)=O] 2 Y(μ 2 -Cl) 2 L-(THF) 2 ( IV ). The molecular structures of complexes I , III , and IV are determined by X-ray diffraction analysis (CIF files CCDC nos. 2001131 ( I ), 2001132 ( III ), and 2001133 ( IV )). Complex IV in the crystalline state exists as an ate complex with one LiCl molecule. Complexes I , III , and IV are catalysts of ring-opening polymerization of ε-caprolactone in toluene at 25°С.