Table 3.

Geometric and electronic structural parameters and energetics of 2a and 2b, as well as of the crystal structure of the hydroperoxy bridged intermediate.¹

	2a2	2b	2a3	2b	crystallography
dielectric constant for PCM	20.0	20.0	4.0	4.0
energy (kcal/mol)
ΔE	0.0	1.0	2.9	0.0
ΔH	0.0	1.2	2.7	0.0
ΔG	0.0	0.2	3.7	0.0
bond length (Å)
Fe—O(1)	2.065	2.366	2.058	2.376	2.1
O—O	1.463	1.470	1.469	1.470	1.5
C2—O(2)	1.518	1.504	1.501	1.505	1.4
Fe—O(C1)	2.137	2.046	2.127	2.050	2.2
Fe—O(C2)	1.990	1.997	2.005	2.000	2.3
C1—O	1.279	1.278	1.280	1.276	1.3
C2—O	1.370	1.363	1.369	1.361	1.5
C1—C2	1.531	1.530	1.532	1.531	1.5
C2(deviation from ring)	0.380	0.385	0.380	0.385	0.46
hydrogen bonds (Å)
O(1)-H	1.523	1.060	1.976	1.049	—
O(1)-N(His200)	2.621	2.623	3.024	2.642	3.0
spin density
Fe	4.03	3.99	4.00	3.98
O(1)	0.06	0.01	0.07	0.01
O(2)	−0.02	−0.02	−0.01	−0.02
O2/O2H	0.04	−0.01	0.06	−0.01
C6(4NC)	−0.43	−0.38	−0.38	−0.36

¹The numbering of atoms is shown in Figure 4.

²Note that geometry optimization with ε = 4.0 was found to converge to 2b from both possible starting structures. Single-point energy using ε = 4.0 with thermal corrections with ε = 20.0 were performed to compare energetics of 2a and 2b below.

³The optimized structure using ε = 4.0 with O(1)-N(His200) fixed. The energies relative to 2b optimized under the same condition as 2a and the thermal corrections with ε = 20.0 were applied to both 2a and 2b.