ortho-metalation of aromatic ethers by yttrium alkyl complexes that contain a linked amido-cyclopentadienyl ligand

The reaction of the half-sandwich alkyl complex [Y(eta(5):eta(1)-C5Me4CH2SiMe2N'Bu)(CH2SiMe3)(THF)] (1) with anisole smoothly gives the ortho-metalation product [Y(eta(5):eta(1)-(C5Me4CH2SiMe2NBu)-Bu-t)(2-C6H4OMe)(THF)] (2). 3- and 4-Methylanisole as well as phenetole analogously undergo ortho-metalation, whereas thioanisole, N,N'-dimethylaniline, fluorobenzene, and trifluorobenzene do not react with yttrium. complex 1. 2-Methylanisole reacts with 1 under activation of the ring methyl group to give the 2-methoxybenzyl complex [Y(eta(5):eta(1)-(C5Me4CH2SiMe2NBu)-Bu-t)(CH2C6H4OMe-2)(THF)] (6). A single-crystal X-ray structure analysis of the 2-anisyl complex 2 revealed a four-legged piano-stool configuration with the methoxy group coordinated cis to the amido-function of the ancillary ligand. (C) 2003 Elsevier B.V. All rights reserved.