Preparation and reactivity of macrocyclic rhodium(III) alkyl complexes

Macrocyclic rhodium(II) complexes LRh(H2O)2+ (L = L1 = cyclam and L2 = meso-Me6-cyclam) react with alkyl hydroperoxides RC(CH3)2OOH to generate the corresponding rhodium(III) alkyls L(H2O)RhR2+ (R = CH3, C2H5, PhCH2). Methyl and benzyl complexes can also be prepared by bimolecular group transfer from alkyl cobaloximes (dmgH)2(H2O)CoR and (dmgBF2)2(H2O)CoR (R = CH3, PhCH2) to LRh(H2O)2+. The new complexes were characterized by solution NMR and by crystal structure analysis. They exhibit great stability in aqueous solution at room temperature, but undergo efficient Rh–C bond cleavage upon photolysis.