Table 2.
Relative energies of the various structures obtained
| Structure | BS | TP | TZ | Free | B3 | B3Free |
|---|---|---|---|---|---|---|
| End-on NNH2 binding | ||||||
| Fe1 | BS7-235 | 111 | 93 | 100 | 120 | |
| Fe2 | BS7-235 | 115 | 91 | 135 | 130 | |
| Fe3 | BS10-147 | 107 | 122 | 132 | 169 | |
| Fe4 | BS7-235 | 163 | 215 | 209 | 213 | |
| Fe5 | BS7-235 | 178 | 169 | 179 | 128 | |
| Fe6 | BS10-147 | 56 (71) | 44 | 91 | 90 (122) | 70 |
| Fe6(HCA) | BS10-135 | 38 (47) | 28 (47) | 52 (70) | 68 (90) | 51 |
| Fe6(HNNH2) | BS10-147 | 9 | 3 | 23 | 29 | 50 |
| Fe6(S2B) | BS10-127 | 87 | 61 | 144 | 138 | |
| Fe7 | BS7-235 | 121 | 130 | 162 | 118 | |
| Fe3(S2A) | BS7-235 | 136 | 159 | 177 | 113 | |
| Fe2/4 | BS7-235 | 168 | 158 | 188 | 192 | |
| Fe3/4 | BS7-235 | 78 | 75 | 110 | 107 | |
| Fe2/6/7 | BS7-235 | 230 | 235 | 207 | 287 | |
| Fe2/6(5) | BS10-147 | 183 | 171 | 185 | 230 | |
| Fe3/7(2) | BS5-256 | 155 | 171 | 145 | 234 | |
| Fe3/7(3) | BS7-235 | 102 | 143 | 152 | 182 | |
| Fe4/5(2) | BS7-235 | 171 | 161 | 195 | 193 | |
| Fe4/5(5) | BS7-235 | 77 | 84 | 114 | 125 | |
| Fe2/3/6/7 | BS7-235 | 230 | 235 | 220 | 287 | |
| Fe2/4/5/6 | BS7-235 | 233 | 240 | 225 | 310 | |
| Fe3/4/5/7 | BS7-235 | 111 | 116 | 139 | 216 | |
| Side-on cis-HNNH binding | ||||||
| Fe2Fe2 | BS10-147 | 107 | 94 | 157 | 164 | |
| Fe4Fe4 | BS10-147 | 217 | 197 | 163 | 340 | |
| Fe5Fe5 | BS10-146 | 196 | 243 | 166 | 283 | |
| Fe6Fe6 | BS7-235 | 197 | 166 | 200 | 167 | |
| Fe7Fe7 | BS7-235 | 150 | 136 | 195 | 205 | |
| Fe2/3Fe6/7 | BS7-235 | 242 | 257 | 215 | 278 | |
| Fe2/6Fe3/7 | BS7-235 | 185 | 177 | 221 | 248 | |
| Fe2/6Fe3/7trc | BS6-156 | 70 | 90 | 128 | 257 | |
| Fe2/4Fe5/6 | BS2-234 | 220 | 211 | 243 | 296 | |
| Fe2/6Fe4/5 | BS3-134 | 276 | 269 | 215 | 413 | |
| Fe2/6Fe4 | BS7-235 | 225 | 273 | 178 | 381 | |
| Fe3/7Fe4/5 | BS2-234 | 40 (59) | 31 (64) | 85 | 186 (183) | 192 |
| Fe2Fe7 | BS7-235 | 204 | 223 | 221 | 203 | |
| Fe3Fe6 | BS10-147 | 199 | 244 | 185 | 252 | |
| Fe2Fe6(3) | BS10-147 | 115 | 99 | 161 | 165 | |
| Fe2Fe6(5) | BS7-235 | 179 | 189 | 215 | 207 | |
| Fe3/7Fe3(2) | BS8-245 | 117 | 114 | 155 | 246 | |
| Fe3Fe7(3) | BS5-256 | 113 | 106 | 135 | 206 | |
| Fe4/5Fe5(2) | BS7-235 | 156 | 143 | 207 | 262 | |
| Fe4Fe5(5) | BS2-234 | 120 | 125 | 150 | 236 | |
| End-on trans-HNNH binding | ||||||
| Fe2(trans) | BS10-147 | 0 | 0 | 0 | 0a | 0a |
| Fe3(trans) | BS10-146 | 69 | 64 | 90 | 88 | |
| Fe4(trans) | BS7-235 | 29 | 28 | 63 | 75 | 35 |
| Fe5(trans) | BS10-147 | 158 | 149 | 109 | 206 | |
| Fe6(trans) | BS10-147 | 10 | 19 | 29 | 35b | 62 |
| Fe7(trans) | BS10-147 | 143 | 136 | 100 | 248 | |
| End-on cis-HNNH binding | ||||||
| MoFe6(cis) | BS7-235 | 176 | 213 | 215 | 162 | |
| Fe2(cis) | BS10-147 | 17 (51) | 12 (44) | 86 | 18a (36) | 46 |
| Fe3(cis) | BS10-146 | 116 | 102 | 134 | 131 | |
| Fe4(cis) | BS7-235 | 84 | 82 | 107 | 127 | |
| Fe5(cis) | BS7-235 | 124 | 122 | 132 | 84 | |
| Fe6(cis) | BS10-135 | 48 | 32 | 34 | 64 | 51 |
| Fe7(cis) | BS7-235 | 204 | 189 | 198 | 269 | 0 |
Up to five energies are given: TP—TPSS-D3/def2-SV(P) optimised geometries with surroundings fixed, TZ—single-point TPSS-D3/def2-TZVPD on the TP structures, Free—TPSS-D3/def2-SV(P) optimised geometries with the surroundings relaxed, B3—B3LYP-D3/def2-SV(P) optimised geometries with surroundings fixed and B3Free—B3LYP-D3/def2-SV(P)-optimised geometries with the surroundings relaxed. Column BS indicates the studied (best) BS state. If additional energies are given in brackets, they are for the BS7-235 state. In some cases, the best BS state is different for TPSS and B3LYP; then the best B3LYP state is indicated in a footnote
aBS8-236
bBS2-267
cIn this structure, one of the protons of HNNH has moved to S5A, whereas the ligand has taken a proton from Arg-96 (cf. Figure S2)