Figure 8.

Empirical plot of DMDH methyl shifts as a function of the angle φ between the unique π-plane of the axial ligand that serves as the stronger π-donor to the iron in a S = 1/2, (d_xy)²(d_xz,d_yz)³ ferrihemoprotein. (27, 44) The angle, φ, is defined in Figure 2A. The pattern of the observed DMDH methyl shifts, and the corresponding φ, are indicated by vertical arrows under CN⁻ (for the cyanide complex) and under ${\mathrm{N}}_3^{-}$ (for the azide complex).