. Author manuscript; available in PMC: 2017 Apr 20.

Published in final edited form as: J Am Chem Soc. 2016 Apr 12;138(15):5110–5122. doi: 10.1021/jacs.6b01151

Table 1.

Spectroscopic Characteristics of SyrB2 Br–Fe^IV═O vs (TMG₃tren)Fe^IV═O Species As Derived from Analyses of MCD/Abs Data in Figure 2, and Band Assignments

	SyrB2-Br			TMG₃tren
feature^a	type of the MCD feature	C₀/D₀^b	band polarization^c	type of the MCD feature	C₀/D₀^b	band polarization^c	band assignment
I	pseudo-A term	0.150	x/y	pseudo-A term	0.250	x/y	LF
II	negative C term	0.005	z	negative C term	0.040	z	oxo-to-Fe CT
III	positive C term	0.050	z	positive C term	0.002	z	oxo-to-Fe CT

MCD and Abs spectral features labeled as I, II, and III in Figure 2.

C₀/D₀ = k_BT/μ_BH(Δε/ε)_max.

As shown in Figure S4, polarization directions depend on the signs of the spin-Hamiltonian zero-field splitting (ZFS) parameters (axial D and rhombic E) which were determined from the fit of VT MCD data: (i) (SyrB2)Fe^IV═O: D = +7 cm⁻¹ and E/D = 0.02; (ii) (TMG₃tren)Fe^IV═O D = +5 cm⁻¹ and E/D = 0.02 from ref 15a.