Analysis of the L-band EPR spectrum of 63Cu(II)–PrPf2 component 2. (A) Pseudomodulated derivative of the experimental L-band spectrum (i.e., the ∂2χ″/∂B2 spectrum) of component 2 (faint line) and simulations assuming two coordinated nitrogen atoms (thick and dashed lines) are shown overlaid. The simulations assumed either coincident g and A (thick line) or noncoincident g and A with g|| determined from X-band EPR (dashed line). (B) Pseudomodulated derivative of the experimental L-band spectrum (i.e., the ∂2χ″/∂B2 spectrum) of component 2 (thin line) and a simulation assuming three coordinated nitrogen atoms (heavy line) are shown overlaid. Trace C is an experimental (∂χ″/∂B) spectrum of component 2, and D is a ∂χ″/∂B simulation assuming two coordinated nitrogens and calculated from the same parameters used for the dashed line in A. Trace E is the first integral of the modulus of the residual, ∫|[(∂2χ″/∂B2)exp − (∂2χ″/∂B2)sim]| dB, where the residual (∂2χ″/∂B2)exp − (∂2χ″/∂B2)sim was obtained by subtraction of the ∂2χ″/∂B2 three-nitrogen simulation from the ∂2χ″/∂B2 experimental spectrum. Trace F is the corresponding ∫ |[(∂2χ″/∂B2)exp − (∂2χ″/∂B2)sim]| dB for the two-nitrogen simulation. The intensities are expressed as a fraction of the integrated modulus ∫|[(∂2χ″/∂B2)| dB of the two-nitrogen computed spectrum. Inset G shows the residual generated by subtraction of the three-nitrogen computed ∂2χ″/∂B2 spectrum from the experimental ∂2χ″/∂B2 spectrum (thick line), overlaid on the residual generated by subtraction of the three-nitrogen computed ∂2χ″/∂B2 spectrum from the two-nitrogen computed ∂2χ″/∂B2 spectrum (thin line with thick dashes).