Rare-earth metal dichloride and bis(alkyl) complexes containing amidinate-amidopyridinate ligands: synthesis, structure, and reactivity

Abstract

A reaction of anhydrous yttrium chloride with an equimolar amount of lithium amidinateamidopyridinate obtained in situ by metallation of N,N’-bis(2,6-dimethylphenyl)-N-{6-[(2,6-dimethylphenyl)amino]pyridin-2-yl}acetimidamide ((2,6-Me2C6H3)NH(2,6-C6H3N)N(2,6-Me2C6H3)C(Me)=N(2,6-Me2C6H3), L1H) (1) with n-butyllithium in THF at–70 °C was used to synthesize the yttrium dichloride complex (L1)YCl2(THF)2 (2). The lutetium bis(alkyl) complex, namely, N’-(2,6-diisopropylphenyl)-N-(2,6-dimethylphenyl-N-{6-[(2,6-dimethylphenyl)amido]pyridin-2-yl}acetimidoamidinatebis(trimethylsilylmethyl)lutetium (4), was obtained by the reaction of N’-(2,6-diisopropylphenyl)-N-(2,6-dimethylphenyl)-N-(6-((2,6dimethylphenyl)amino)pyridin-2-yl)acetimidamide ((2,6-Me2C6H3)NH(2,6-C6H3N)N-(2,6-Me2C6H3)C(Me)=N(2,6-Pr 2 i C6H3), L2H (3)) with an equimolar amount of Lu(CH2SiMe3)3(THF)2. Complex 4 was found to be very stable and did not show indications of C—H-activation and other kinds of disintegration in benzene or toluene solution even upon prolonged heating at 60 °C. The reaction of complex 4 with an equimolar amount of 2,6-diisopropylaniline in toluene solution at room temperature led to the formation of the lutetium alkyl-anilide complex (L2)Lu(CH2SiMe3)(NH-2,6-Pr 2 i C6H3) (5). A three-component system 4—AlBu 3 i —[X][B(C6F5)4] ([X] = [Ph3C], [PhNHMe2], the molar ratio of 1: 10: 1) was found to catalyze polymerization of isoprene.