Steric effects on acetate-assisted cyclometallation of meta-substituted N-phenyl and N-benzyl imidazolium salts at [MCl2Cp*]2 (M = Ir, Rh).

meta-Substituted N-phenyl,N'-methyl and N-benzyl,N'-methyl imidazolium salts undergo acetate-assisted cyclometallation to provide mixtures of ortho and para substituted cyclometallated complexes. The effect of the substituents on the isomer ratios is discussed; steric effects are more important in the 6-membered rings derived from the N-benzyl imidazolium salts than 5-membered rings from the N-phenyl salts. Comparisons are made to steric effects with some other common directing groups.