Table 1. Vibrational Frequencies (in cm−1) of Fe(III)-Porphyrin-Nitrite Complexes and Other Nitrite Speciesa.
| nitrite species | νas(NO2) or ν (N=O) | νs(NO2) or ν(N–O) | δ(NO2) or δ(ONO) | ν(Fe-NO2) or ν(Fe-ONO) | ref |
|---|---|---|---|---|---|
| 6c Nitro | |||||
| L16G AXCP (exptl) | 1396 (−30, −62) | 1311 (−21, −57) | 816 (−7, −40) | 309 (∼0, −2) | tw |
| L16G AXCP (calcd) | 1588 (−31, −69) | 1428 (−23, −65) | 849 (−8, −43) | 318 (∼0, −1) | tw |
| Fe(TTP)(1-MeIm)(NO2) | 1396 (−33) | 1312 (−21) | 813 (−7) | nd | 46 |
| Fe(TTP)(NH3)(NO2) | 1401 (−34) | 1312 (−21) | 810 (−6) | nd | 46 |
| Fe(TTP)(py)(NO2) | 1405 (−32) | 1306 (−19) | 810 (−6) | nd | 46 |
| HRP | nd | 1272 (−32, −54) | 822 (−7, −44/−24) | 563 (−19, −23) | 27 |
| 6c Nitrito | |||||
| Fe(TTP)(NH3)(ONO) | 1470 (−32) | 969 (−17) | ∼827 (−5) | nd | 46 |
| Mb | 1470 (−35, −70) | 998 (−28, −44) | 818 (−20, −28) | 296/256 (0, −18) | 24, 26 |
| L16G AXCP (calcd) | 1608 (−20, −73) | 1094 (−22, −47) | 886 (−4, −48) | 328 (∼0, −2) | tw |
| 5c Nitrito | |||||
| Fe(TTP)(ONO) | 1528 (−34) | 902 (−23) | 751 (−4) | nd | 47 |
| Nitrovinyl | |||||
| HRP | nd | 1334 (−25, −55) | nd | 27 | |
| Mb | 1518 (−36) | 1324 (−20) | nd | 24, 26 | |
| Free Nitrite | |||||
| NO2−(aq) | ∼1240 | 1325–1331 | 817 | 48, 49 | |
a
Data in italics refer to nitrito vibrations. Values in parentheses indicate frequency shifts upon substitution with 15NO2− and 15N18O2−. Abbreviations: tw, this work; nd, not determined.