HIGH-VALENT MANGANESE IN POLYOXOTUNGSTATES .4. CATALYTIC AND STOICHIOMETRIC ALKENE OXIDATION

Six manganese-containing heteropolytungstates, alpha-[(XO(4))W11MnO36] (n-) (XW(11)Mn; X=P, Si, B, and Zn), gamma-[(SiO4)(W10Mn2O36H6)-O-III] (4-)(SiW10Mn2), and [Mn-4(II)(H2O)(2)(PW9O34)(3)](10-) (P2W18Mn4) have been compared as catalysts for the oxidation of cyclohexene and cis-s tilbene by iodosylbenzene. The yield of epoxide and the cis/trans isom er ratio of stilbene epoxides are dependent upon the charge of the XW( 11)Mn catalysts. In addition to the oxidation reactions, isomerization of cis-stilbene to trans-stilbene was observed when an oxidized deriv ative of P2W18Mn4 was used as a catalyst. Stoichiometric oxidation of cyclohexene or cis-stilbene by high-oxidation-state manganese-substitu ted heteropolyanions eropolyanions was also examined. Product distribu tions from stoichiometric oxidation are different from those from the catalytic reactions for each heteropolyanion, suggesting that differen t reaction pathways may be involved in these two types of reactions.