Table 7. A Comparison of Key Bond Lengths (Å) and Angles (deg) between the ROH- and η²-Bound Structures in the 1e^– Reduced RO^HP^–E^H State.

binding mode	ROH		η2-ring		η2-trans
valence isomer	ααββ	βααβ	ααββ	βααβ	ααββ	βααβ
cluster bond lengths
Fe1–S1	2.282	2.245	2.307	2.285	2.309	2.289
Fe1–S2	2.279	2.267	2.284	2.291	2.279	2.299
Fe1–S3	2.229	2.324	2.241	2.384	2.238	2.375
Fe2–S1	2.336	2.333	2.330	2.316	2.332	2.321
Fe2–S2	2.298	2.213	2.302	2.194	2.307	2.200
Fe2–S4	2.283	2.395	2.270	2.373	2.277	2.370
Fe3–S1	2.260	2.328	2.248	2.311	2.250	2.313
Fe3–S3	2.312	2.258	2.340	2.271	2.331	2.259
Fe3–S4	2.368	2.382	2.362	2.367	2.364	2.366
Fe4–S2	2.272	2.321	2.270	2.312	2.273	2.316
Fe4–S3	2.314	2.307	2.332	2.307	2.327	2.302
Fe4–S4	2.339	2.301	2.343	2.246	2.343	2.252
Fe2–SC13	2.335	2.309	2.310	2.285	2.314	2.292
Fe3–SC197	2.297	2.330	2.300	2.364	2.302	2.356
Fe4–SC96	2.337	2.356	2.295	2.314	2.297	2.315
HMBPP bond lengths
Fe1–OC4	2.340	2.257	4.552	4.287	3.751	3.593
Fe1–C3	3.363	3.304	2.541	2.144	2.615	2.143
Fe1–C2	3.603	3.573	2.496	2.118	2.531	2.112
H-bond lengths
OC4–OT167	3.178	3.174	4.397	4.384	3.424	3.370
OT167–OE126	2.653	2.649	2.693	2.687	2.655	2.634
OE126–OW1	3.686	3.677	3.733	3.598	3.687	3.633
OW1–OPPi	2.730	2.734	2.782	2.774	2.732	2.723
OC4–OE126	4.156	4.154	3.620	3.621	3.149	3.137
OC4–OPPi	4.838	4.852	2.683	2.722	4.541	4.593
HMBPP angle
C2–C3–C4–OC4	–101.4	–101.9	95.2	90.3	–154.8	–158.4