Journal of Molecular Catalysis A-Chemical, Vol.262, No.1-2, 25-29, 2007
A novel Ti-O-Ti bonding species constructed in a metal-oxide cluster [{Ti(OH2)(ox)}(2)(mu-O)(alpha-PW11O39)](5-) as a precatalyst: Epoxidation of alkenes with hydrogen peroxide
A novel Ti-O-Ti bonding complex constructed in the monomeric, mono-lacunary alpha-Keggin polyoxotungstate, [{Ti(OH2)(ox)}(2)(mu-O)(alpha-PW11O39)](5-) (1) can act as a precatalyst for the epoxidation of cyclooctene, cyclohexene, and 1-octene with aqueous H2O2 at 25 degrees C in a homogeneous system. The catalytic activities of complex 1 were considerably higher than those of dimeric mono-, di-, and tri-titanium(IV)-substituted Keggin polyoxotungstates [(alpha-PTiW11O39)(2)O](8-) (2), [(alpha-1,2-PW10Ti2O38)(2)O-2](10-) (3), and [(alpha-1,2,3-PTi3W9O3])(2)O-3](12-) (4). (c) 2006 Elsevier B.V. All rights reserved.