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Yi XY, Zhang QF, Lam TC, Chan EY, Williams ID, Leung WH: Phosphato, chromato, and perrhenato complexes of titanium (IV) and zirconium (IV) containing Klaui's tripodal ligand. Inorg Chem. 2006 Jan 9;45(1):328-35.
Treatment of titanyl sulfate in dilute sulfuric acid with 1 equiv of NaL (OEt) (L (OEt)(-) = [(eta (5)-C (5) H (5)) Co{P (O)(OEt)(2)](3)](-)) in the presence of Na (3) PO (4) and Na (4) P (2) O (7) led to isolation of [(L (OEt) Ti)(3)(mu-O)(3)(mu (3-) PO (4))] (1) and [(L (OEt) Ti)(2)(mu-O)(mu-P (2) O (7))] (2), respectively. The structure of 1 consists of a Ti (3) O (3) core capped by a mu (3)-phosphato group. In 2, the [P (2) O (7)](4-) ligands binds to the two Ti's in a mu:eta (2),eta (2) fashion. Treatment of titanyl sulfate in dilute sulfuric acid with NaL (OEt) and 1.5 equiv of Na (2) Cr (2) O (7) gave [(L (OEt) Ti)(2)(mu-CrO (4))(3)] (3) that contains two L (OEt) Ti (3+) fragments bridged by three mu-CrO (4)(2-)-O,O' ligands. Complex 3 can act as a 6-electron oxidant and oxidize benzyl alcohol to give ca. 3 equiv of benzaldehyde. Treatment of [L (OEt) Ti (OTf)(3)] (OTf (-) = triflate) with [n-Bu (4) N][ReO (4)] afforded [[L (OEt) Ti (ReO (4))(2)](2)(mu-O)] (4). Treatment of [L (OEt) MF (3)] (M = Ti and Zr) with 3 equiv of [ReO (3)(OSiMe (3))] afforded [L (OEt) Ti (ReO (4))(3)] (5) and [L (OEt) Zr (ReO (4))(3)(H (2) O)] (6), respectively. Treatment of [L (OEt) MF (3)] with 2 equiv of [ReO (3)(OSiMe (3))] afforded [L (OEt) Ti (ReO (4))(2) F] (7) and [[L (OEt) Zr (ReO (4))(2)](2)(mu-F)(2)] (8), respectively, which reacted with Me (3) SiOTf to give [L (OEt) M (ReO (4))(2)(OTf)] (M = Ti (9), Zr (10)). Hydrolysis of [L (OEt) Zr (OTf)(3)] (11) with Na (2) WO (4).xH (2) O and wet CH (2) Cl (2) afforded the hydroxo-bridged complexes [[L (OEt) Zr (H (2) O)](3)(mu-OH)(3)(mu (3)-O)][OTf](4) (12) and [[L (OEt) Zr (H (2) O)(2)](2)(mu-OH)(2)][OTf](4) (13), respectively. The solid-state structures of 1-3, 6, and 11-13 have been established by X-ray crystallography. The L (OEt) Ti (IV) complexes can catalyze oxidation of methyl p-tolyl sulfide with tert-butyl hydroperoxide. The bimetallic Ti/ Re complexes 5 and 9 were found to be more active catalysts for the sulfide oxidation than other Ti (IV) complexes presumably because Re alkylperoxo species are involved as the reactive intermediates. |
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