Table 11. A Comparison of Key Bond Lengths (Å) and Angles (deg) between the ROH- and η²-ring Structures in Both the Oxidized and 1e^– Reduced RO^HP^–E^H States.

	oxidized				reduced
binding mode	ROH	ROH	η2-ring		η2-ring
valence isomer	αββα	βααβ	αββα	βααβ	αββα	βααβ
cluster bond lengths
Fe1–S5	2.200	2.200	2.197	2.197	2.207	2.285
Fe1–S6	2.282	2.282	2.277	2.278	2.298	2.291
Fe1–S7	2.319	2.319	2.304	2.304	2.308	2.384
Fe2–S5	2.328	2.328	2.305	2.304	2.302	2.316
Fe2–S6	2.206	2.206	2.193	2.192	2.225	2.194
Fe2–S8	2.357	2.357	2.358	2.360	2.361	2.373
Fe3–S5	2.305	2.305	2.300	2.300	2.285	2.311
Fe3–S7	2.240	2.240	2.265	2.267	2.320	2.271
Fe3–S8	2.361	2.361	2.350	2.349	2.344	2.367
Fe4–S6	2.326	2.326	2.309	2.310	2.318	2.312
Fe4–S7	2.322	2.322	2.325	2.324	2.343	2.307
Fe4–S8	2.241	2.241	2.229	2.230	2.256	2.246
Fe2–SC12	2.256	2.256	2.241	2.238	2.290	2.285
Fe3–SC197	2.275	2.275	2.285	2.284	2.281	2.364
Fe4–SC96	2.295	2.295	2.279	2.279	2.338	2.314
HMBPP bond lengths
Fe1–OC4	2.214	2.214	4.514	4.516	4.525	4.287
Fe1–C3	3.531	3.531	2.603	2.604	2.552	2.144
Fe1–C2	3.272	3.272	2.571	2.569	2.485	2.118
H-bond lengths
OC4–OT167	3.189	3.189	4.334	4.342	4.380	4.384
OT167–OE126	2.661	2.661	2.700	2.702	2.684	2.687
OE126–OW1	3.687	3.688	3.703	3.685	3.717	3.598
OW1–OPPi	2.734	2.734	2.794	2.793	2.786	2.774
OC4–OE126	4.209	4.209	3.629	3.641	3.590	3.621
OC4–OPPi	4.875	4.875	2.695	2.695	2.703	2.722
HMBPP angle
C2–C3–C4–OC4	–101.5	–101.5	95.4	95.7	94.1	90.3