The IR spectral data assignments for complexes 1 and 2 and their appropriate ligands 2- and 3-pyridylphosphonic acids.
| 2-pypoH2 | Complex 1 | 3-pypoH2 | Complex 2 | |
|---|---|---|---|---|
| ν(O–H) | 3480–3300 | — | 3550–3180 | — |
| ν(CH) | 3108, 3082 | 3054, 3007 | 3118, 3084 | 3110, 3078 |
| ν(C–C), ν(C–N) | 1608, 1520, 1443, 1389 | 1583, 1562, 1459, 1420 | 1626, 1548, 1460, 1368 | 1598, 1566, 1478, 1417 |
| ν(PO3) | 1157,1091, 1030 | 1164, 1154, 1031 | 1178, 1112, 1034 | 1196, 1159, 1118 |
| ν(C–P) | 939 | 948 | 932 | 923 |
| ν(NO3−) | — | 1316 | — | — |
| δ(PO3) | 553, 513, 439 | 570, 528, 460 | 535, 511, 443 | 555, 485, 450 |
| γ(C–H) | 765, 717 | 760, 726 | 727, 682 | 748, 703 |