Natural peptide sequences ligate to dirhodium centers through two bridging aspartate side chains, creating a macromolecular ligand framework with helical structure. The generation of a small peptide library allowed optimization of peptide sequence and produced an efficient catalyst for enantioselective carbenoid insertion into Si-H bonds. Analysis of the library indicates that the i-1 and i+3 positions of nonapeptides have the most significant effect on enantioselectivity, though the structural basis for selectivity is different at each of the positions.