Table 1.
Backbonding correlationsa of Fe-XO (X=C, N, O) adducts derived from ν(Fe-X) and ν(XO) frequencies.
| Experiment | DFT | ||||
|---|---|---|---|---|---|
| Compound | ν°(Fe-X)(cm-1) | Slope(s) | Compound | ν°(Fe-X)(cm-1) | Slope(s) |
|
Fe-CO adducts Five –coordinate Fe(II)TPP-Y Six-coordinate Mb and Fe(II)TPP-Y(trans-ImH) NOS [trans-Cys...H-bond] P450cam [trans-Cys] |
425 346 366 339 |
-0.52 -0.81 -0.62 -0.68 |
Fe(II)P-X Fe(II)P-X(trans-py)b Fe(II)P-X(trans-SCH3–)b |
536 263 200 |
-0.57 -1.54 -1.49 |
|
Fe-NO adducts Six-coordinate MbIIINO[trans-His] + distal His MbIIINO[trans-His] - distal His |
644 627 |
-1.1 -1.2 | Fe(III)P-X[trans-ImH] Fe(III)P-X[trans-ImH]+distal His |
872 931 |
-1.1 -1.3 |
|
Fe-NO adducts Five –coordinate Fe(II)TPP-Y Six-coordinate Fe(II)TPP-Y[trans-ImH] |
445 329 |
-0.40 -1.0 |
Fe(II)P-X Fe(II)P-X[trans-ImH]+ONO...H bond |
581 552 |
-0.26 -0.24 |
|
Fe-OO adducts Five –coordinate Fe(II)TPP-Y/P-X Six-coordinate |
425 | -0.79 | Fe(II)P-X Fe(II)P-X[trans-ImH] |
240 320 |
-0.86 -0.74 |
a
ν0XO = ν0MX – s[νXO – ν0XO]; ν°XO values in the gaseous states of CO = 2145 cm-1, NO = 1876 cm-1 and OO = 1556 cm-1.
b
Values from ref.[16].