Complexes of tungsten(IV,VI) derived from linked aryloxide ligands

Biphenoxo complexes of tungsten(VI), [WCl4{CHR[C6H2(But)2O]2}] R = H (1), Me (2) are reduced by Na/Hg in the presence of PMe3 to give cis, trans-WCl2(PMe3)2{CHR[C6H2(But)2O]2} R = H (3), Me (4). Reaction of [WOCl4] with the biphenols 2,2′-CHR[C6H2(But)2OH]2 in diethyl ether gives [WOCl2{CHR[C6H2(But)2O]2}] R = H (5), Me (6). Similar treatment of [W(NPh)Cl4(Et2O)] gives the complex [W(NPh)Cl3{(1,1′-O,OH)(2,2′-CH3CH)[4,6-(But)2C6H2]2}] (7) containing the monoanionic ligand {(1,1′-O,OH)(2,2′-CH3CH)[4,6-(But)2C6H2]2}-. Reaction of [WOCl4] with the linear triphenol 2,6-bis(3,5-di-t-butyl-2-hydroxybenzyl)-4-methylphenol, HOArCH2Ar1(OH)CH2ArOH (Ar = 4,6-di-t-butylphenol; Ar1 = 4-methylphenyl), in refluxing toluene affords the centrosymmetric complex {WOCl[OArCH2Ar1(O)CH2ArO]}2 (8), in which the mer-tridentate ligands adopt the U-conformation. The related complex {WOCl[OAr2CH2Ar3(O)CH2Ar2O]} (9) has been isolated as a hydrolysis product from the reaction of [W(NPh)Cl4(Et2O)] and 2,6-(3-t-butyl-5-methyl-2-hydroxybenzyl)-4-t-butylphenol, HOAr2CH2Ar3(OH)CH2Ar2OH (Ar2 = 4-methyl-6-t-butylphenol; Ar3 = 4-t-butylphenyl), and is also available via [WOCl4]. Reaction of [W(eg)3] (eg = 1,2-ethanediolato) with 2,6-bis(3,5-methyl-2-hydroxybenzyl)-4-t-butylphenol, HOAr4CH2Ar3(OH)CH2Ar4OH(Ar4 = 4,6-di-methylphenol) affords [W(eg)2(OAr4CH2Ar3(O)CH2Ar4OH)] (10), containing a chelating biphenolate ligand with a pendant phenolic group. Crystal structures of complexes 1, 3, 5, 8, 9 and 10 are reported. © 2006 Elsevier Ltd. All rights reserved