Intramolecular (sp3-hybridized) C-H activation:: yttrium alkyls versus transient yttrium Hydrides

Intramolecular sp(3)-hybridized C-H activation of novel yttrium alkyl and hydrido complexes supported by bulky aminopyridinato ligands derived from deprotonated 2,6-(diiso-propylphenyl)-[6-(2,6-dimethylphenyl)pyridin-2-yl]amine (Ap '-H) is reported. Reaction of YCl3 with a 2-fold molar excess of Ap ' K in THF afforded complex [Ap ' 2YCl(thf)] (1). Alkylation of I with an equimolar amount of LiCH2SiMe3 in hexane allowed isolation of the alkylyttrium derivative [AP ' 2yCH(2-)SiMe(3)(thf)] (2) in 65% yield. Unexpectedly treatment of complex 2 with PhSiH3 (toluene, 20 degrees C) afforded the product of intramolecular sp(3)-hybridized C-H bond activation, Ap '(AP '-H) Y(THF) (3). Most likely a hydrid species is formed in the course of this reaction, which undergoes rapid C-H activation since 3 is formed from 2 directly about 500 times slower than in the presence of 1 equiv of PhSiH3. Molecular structures of complexes 2 and 3 have been confirmed by X-ray crystal structure analysis.