Figure 4. Steric descriptors of Cp^X ligands.

(A) Definition of the Tolman cone angle for a Cp^X ligand with two substituent types (R_S and R_L). α_i = angle between the vector defined by the Rh-Cp(centroid) axis and the vector tangential to the outermost atomic sphere (H_max) of each substituent R_i; d_i = distance between the Rh atom and the center of H_max; θ_i = half-vertex angle to H_max corrected for atomic VdW radius; r_H = VdW radius of H_max; Θ = averaged cone angle for the entire ligand. (B) Definition of Sterimol parameters. All angles and distances are measured on CPK models. B₁ = minimum width of the Cp^X ligand perpendicular to the Rh-Cp(centroid) axis; B₅ = maximum width; L = Rh-Cp(centroid) distance.