Table 3: FT-IR spectra of ML, FL free ligands and their complexes 1–6.
| Compound | υ (C=O) (COOH) | υ (C=O) amide(I) (N−C=O) | υ (OH) | υ (C−H) aromatic | υ (C−O) (OCOH) | υ (NH) amide | υ (M−O) | υ (C=O) carbonyl | υ (M−C) |
| ML | 1,699 s | 1,620 m | 3,262 s | 3,068 w | 1,304 m | 3,198 w | — | — | — |
| 3,000 w | |||||||||
| FL | 1,702 s | 1,595 m | 3,270 s | 3,093 w | 1,320 m | 3,209 w | — | — | — |
| 3,050 w | |||||||||
| Cr(CO)6 | — | — | — | — | — | — | — | 2,043 s | 600 |
| Mo(CO)6 | — | — | — | — | — | — | — | 2,000 s | 550 |
| W(CO)6 | — | — | — | — | — | — | — | 2,073 s | 540 |
| 1 | 1,710 s | 1,611 m | 3,049 | 3,073 w | 1,243 m | 3,409 w | 550 | 2,047-1,935-1,869 | 527 s |
| 3,020 w | |||||||||
| 2 | 1,705 s | 1,625 m | 3,436 | 3,067 w | 1,243 m | 3,436 w | 558 | 2,049-1,914-1,872 | 521 m |
| 3,010 w | |||||||||
| 3 | 1,707 s | 1,632 m | 3,425 | 3,063 w | 1,241 m | 3,429 w | 594 | 2,049-1,918-1,873 | 520 m |
| 3,017 w | |||||||||
| 4 | 1,704 s | 1,657 m | 3,342 | 3,072 w | 1,217 m | 3,294 w | 516 | 2,208-1,953-1,878 | 542 m |
| 3,092 w | |||||||||
| 5 | 1,701 s | 1,633 m | 3,420 | 3,067 w | 1,221 m | 3,255 w | 601 | 2,076-1,903-1,879 | 487 m |
| 3,016 w | |||||||||
| 6 | 1,702 s | 1,633 m | 3,416 | 3,066 w | 1,219 m | 3,250 w | 595 | 2,056-1,901-1,876 | 485 m |
| 2,970 w | |||||||||