Table 3. Infrared Spectral Bands (cm–1) and Their Assignments for All Synthesized Compounds.
| compounds/bands | |||||||
|---|---|---|---|---|---|---|---|
| assignment | H4L | Mn(II) | Co(II) | Ni(II) | Cu(II) | Zn(II) | Fe(III) |
| υ(OH) | 3451 | 3446 | 3453 | 3469 | 3449 | 3449 | 3417 |
| υ(NH) | 3094 | 3140 | 3015 | 3156 | 3077 | 3140 | - |
| υ(C–H)TBA | 2824 | 2869 | 2844 | 2821 | 2952 | 2857 | 2873 |
| υ(S–H) | 2594 | 2621 | 2623 | 2594 | 2546 | 2596 | 2613 |
| υ(C=S) | 720 | - | - | - | - | - | - |
| υ(C=O) | 1708, 1672 | 1735, 1687 | 1733, 1697 | 1718, - | 1718, - | 1734, 1679 | 1735, 1688 |
| υ(C=N) | 1639 | 1623 | 1642 | 1620 | 1616 | 1626 | 1638 |
| δ(NH) | 1520 | 1530 | 1536 | 1521 | 1528 | 1559 | 1524 |
| γ(NH) | 788 | 798 | 797 | 787 | 767 | 792 | 795 |
| υ(N=N) | 1421, 1411 | 1421 | 1422 | 1418 | 1400 | 1418 | 1418 |
| υ(C–N) + υ(C–O) + υ(M–OH) | 1178, 1064 | 1104 | 1156, 1098 | 1142, 1104 | 1165, 1048 | 1187, 1112 | 1106 |
| υ(N–C=O) | 580 | 580 | 609 | 578 | 598 | 619 | 618 |
| υ(C–C=O) | 529 | 529 | 540 | 531 | 530 | 530 | 534 |
| γ(C=O) + υ(M–O) | 456 | 456 | 437 | 484 | 437 | 438 | 469 |
| υ(M–N) + υ(M–S) | - | 406 | 422 | 422 | 422 | 421 | 422 |