Hydrosilylation of dienes by yttrium hydrido complexes containing a linked amido-cyclopentadienyl ligand
Abstract
The dimeric hydrido complex [Y(L)(THF)(μ-H)]2 (2) containing the CH2SiMe2-linked amido-cyclopentadienyl ligand L = C5Me4CH2SiMe2NCMe32− catalyzed the hydrosilylation of 1,5-hexadiene, 1,7-octadiene and vinylcyclohexene by PhSiH3. As demonstrated for 1,7-octadiene, the product distribution of the hydrosilylation strongly depends on the molar ratio of the reagents. In the absence of PhSiH3, the stoichiometric reaction of 2 with 1,5-hexadiene gave the isolable crystalline cyclopentylmethyl complex [Y(L){CH2CH(CH2)4}(THF)] (3). Internal olefins such as trans-stilbene and alkynes such as tert-butylacetylene were not hydrosilylated by 2. trans-Stilbene was inserted into the yttrium–hydride bond of 2 to give the 1,2-diphenylethyl complex [Y(L){CH(CH2Ph)Ph}(THF)] (4). tert-Butylacetylene reacted with 2 to give the dimeric acetylide [Y(L)(CCCMe3)]2 (5). In an attempt to detect the monomeric hydrido species as a DME adduct [Y(L)H(DME)], complex 2 was reacted with DME to form the sparingly soluble, dimeric 2-methoxyethoxy complex [Y(L)(μ-OCH2CH2OMe-κO)]2 (6) under C–O splitting.