Reactions of active methylene compounds HA (malononitrile, \u3b2-diketones, cyclopentadiene) with the dioxygen adduct [Rh(dppe)O2]BF4 give new hydroperoxorhodium(III) complexes of the type [Rh(dppe)(A)OOH]BF4. The complexes readily convert PPh3 into OPPh3, but do not oxidise ketones or olefins, which instead undergo extensive isomerization