Experimental band positions and strengths (s = strong, m = medium, w = weak) accompanied by theoretical calculated frequencies, intensities, and descriptions for the assigned structures.
| Experiment | Theory B3LYP/CCSDa | Mode description | |||
|---|---|---|---|---|---|
| Frequency (cm−1) | Strength | Frequency (cm−1) | Intensity (km mol−1) | ||
| FeCH2+ (4B1) | 554/570 | 36/45 | CH2 rocking | ||
| 632 | s | 627/647 | 5/43 | M–C stretch | |
| 767 | m | 787/754 | 101/106 | CH2 wagging | |
| — | — | 1321/1358 | 1/1 | CH2 scissor | |
| FeCH2+ (4B2) | 555/567 | 40/50 | CH2 rocking | ||
| 632 | s | 632/646 | 9/43 | M–C stretch | |
| 767 | m | 716/744 | 69/98 | CH2 wagging | |
| — | — | 1319/1359 | 0/1 | CH2 scissor | |
| CoCH2+ (3A2) | 622/625 | 36/41 | CH2 rocking | ||
| 673 | s | 631/690 | 0/25 | M–C stretch | |
| 811 | s | 877/861 | 88/100 | CH2 wagging | |
| 948 | m | 1377/1410 | 3/23 | CH2 scissor | |
| CoCH2+ (3A1) | 601/624 | 31/39 | CH2 rocking | ||
| 673 | s | 625/693 | 1/14 | M–C stretch | |
| 811 | s | 893/881 | 89/100 | CH2 wagging | |
| 948 | m | 1382/1416 | 3/30 | CH2 scissor | |
a
B3LYP and CCSD calculations used the def2-TZVPPD basis set.