- Previous Article
- Next Article
- Table of Contents
Inorganic Chemistry, Vol.46, No.20, 8426-8434, 2007
Anisole-diphenoxide Ligands and their zirconium dichloride and dialkyl complexes
Linear triphenol H-3[O-R(3)] (2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-R-phenol; R = Me, Bu-t) was found to undergo selective mono-deprotonation and mono-O-methylation. Deprotonation of H-3[O-R(3)] with 1 equiv of (BuLi)-Bu-n resulted in the formation of Li{H-2[O-R(3)]}(Et2O)(2) (R = Me (1a), Bu-t (1b)), in which the central phenol unit was lithiated. Treatment of H-3[O-R(3)] with methyl p-toluenesulfonate in the presence of K2CO3 in CH3CN gave the corresponding anisol-diphenol H-2[(O2O)-O-R] (2,6-bis(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4-R-anisole; R = Me (2a), Bu-t (2b)). Reaction of H-2[(O2O)-O-R] with 2 equiv of (BuLi)-Bu-n gave the dilithiated derivatives Li-2[(O2O)-O-R]. The lithium salts were reacted with ZrCl4 in toluene/THF to obtain the dichloride complex [(O2O)-O-R]ZrCl2(thf) (R = Me (3a), Bu-t (3b)). 3b underwent dimerization along with a loss of THF to generate {[(O2O)-O-tBu]ZrCl2}(2) (4), whereas 4 was dissolved in THF to regenerate the monomer 3b. Alkylation of 3 with MeMgBr, PhCH2MgCl, and Me3SiCH2MgCl gave [(O2O)-O-Me]-ZrMe2(thf) (5), [(O2O)-O-R]Zr(CH2Ph)(2) (R = Me (6a), Bu-t (6b)), and [(O2O)-O-tBu]Zr(CH2SiMe3)(2) (7), respectively. Reaction of 3b with LiBHEt3 produced the hydride-bridged dimer [Li-2(thf)(4)Cl]{[O-tBu(3)]Zr}(2)(mu-H)(3)} (8), in which demethylation of the dianionic [(O2O)-O-tBu] ligand took place to give the trianionic [O-tBu(3)] ligand. The X-ray crystal structures of 1b, 2a, 3a, 4, 6a, and 7 were reported.