Trigonal Bipyramidal Rhodium(I) Methyl and Phenyl Complexes: Precursors of Oxidative Methyl and Phenyl Radical Generation

The new complexes [Rh(Me)(trop(3)P)] (2) and [Rh(Ph)(trop(3)P)] (3) (trop = 5H-dibenzo[a,d]cyclohepten-5-yl) were synthesised by addition of organolithium reagents (MeLi and PhLi) to the parent pentacoordinated chloride complex [RhCl(trop(3)P)]. The compounds have a trigonal bipyramidal structure with olefin-only ligands in the equatorial position and the methyl or phenyl substituent in the axial position. Oxidation of complexes 2 and 3 leads to the liberation of methyl and phenyl radicals, which were indirectly detected by reaction with common spin trapping reagents.