CATALYTIC AIR OXIDATION OF THIOLS MEDIATED AT A MO(VI)O-2 COMPLEX CENTER INTERCALATED IN A ZN(II)-AL(III) LAYERED DOUBLE HYDROXIDE HOST

While bis(2-mercapto-2,2-diphenyl-ethanoate) dioxomolybdate (VI), {MoO2[OOCC(S)(C6H5)(2)](2)}(2-) (I), ethanolic solutions stoichiometrically react with aromatic and aliphatic thiols to give the corresponding disulfides, the intercalation of I within a Zn(II)-Al(III) layered double hydroxide (LDH) allows their catalytic oxidation by dioxygen. A reaction scheme is proposed in which a (MoO)-O-IV species activates O-2, regenerating the parent (MoO2)-O-VI complex (I), which then acts as a true catalyst. Kinetic data far the thiol oxidation reaction have been determined. The results obtained here demonstrate that the intercalation of I into a Zn(II)-Al(III) LDH host inhibits the formation of catalytically inactive (MoO)-O-V species that are always formed under homogeneous conditions. (C) 1995 Academic Press, Inc.