Higher grade reagents and solvents were commercially available (Fluka A.G., Merck, BDH) and used as received. Infrared spectra were recorded on a Nicolet 100 FTIR spectrophotometer in the 400 - 4000 cm⁻¹ range using KBr discs. NMR spectroscopy recorded by Av 300 instrument. Conductivity measurements were carried out on 10⁻³ M solution of the complexes in DMF using conductivity meter Jenway PCM3 at an ambient temperature. The electronic spectra were recorded on a PgT92+ UV-visible spectrophotometer for 10⁻³ M solutions of complexes in DMF as solvent at 25˚C using 1 cm quartz cell. Melting points were recorded on an Electrothermal 9300 apparatus. The magnetic susceptibility measurements were carried out at 25˚C on the solids by Gouy’s method using Sherwood Scientific instrument.

To a mixture of 2,6-diaminopyridine (0.109 g, 0.001 mol) and 2-hydroxyben- zaldehyde (0.2442 g, 0.002 mol) add drop of glacial acetic acid were placed in the microwave oven and irradiated at 400 W for 1 min. Then left to cool to room temperature. The solid so formed was filtered and recrystallized from ethanol.

To an ethanoic solution of (LH) (0.317 g, 0.001 mol) was added dropwise to each ethanoic solution of CoCl₂∙6H₂O (2.30 g, 0.001 mol), NiCl₂∙6H₂O (2.36 g, 0.001 mol), CuSO₄ (0.167 g, 0.001 mol), ZnCl₂ (0.136 g, 0.001 mol) and CdCl₂ (0.183, 0.001 mol) with a stirring at a room temperature the precipitate formed was filtered off, washed with 10 ml of water and dried under vacuum.

The most important of infrared frequencies of Schiff base and its Co(ΙΙ), Ni(II), Cu(II), Zn(ΙΙ), Cd(ΙΙ) complexes are recorded in Table 2. The spectrum of ligand showed the absence of C=O absorption band at 1850 - 1650 cm⁻¹. And appearance of a new band at (1601) cm⁻¹ due to azomethine spectra, suggest the formation of ligand [13] [14] . The ligand spectra show a broad band at 3375 cm⁻¹ due to stretching vibration of υ (O-H), as well as the C-N band at 1454 cm⁻¹, the band at 1601 cm⁻¹ assign to υ (C=N ), and the υ (C-O) band at 1277 cm⁻¹ [15] . The prepared complexes exhibited very comparable IR features, suggesting that they are of similar structure [16] . In the complexes the absorption band of stretching vibrations υ (O-H) disappeared which is assigned to the complexes formation [17] . The complexes shown absorption bands (1608 - 1613) cm⁻¹ due to υ (C=N) shifted to higher frequency compared with ligand [18] [19] . And absorption band of υ (C-N) shows a shifted to lower frequency assign to coordination [7] . The bands in the region of (586 - 421) cm^-1 confirm the nature of the metal-ligand bonding [20] .

The ¹HNMR spectrum of ligand (LH), Figure 1 in DMSO-d⁶ solvent shows a signal at (δ = 10.27 ppm) equivalent to two protons assigned to (O-H) group of carbon [21] . Two protons of (N=C-H) imine group appears as a signal at (δ = 9.31, 9.96 ppm). The multiplet signals at (δ = 6.11 ppm), (6.68), (6.9), (7.0), (7.35), (7.48), (7.53), (7.95) ppm are due to aromatic hydrogen of carbon [22] .

The electronic spectra of ligand appeared two band at (26,455, 35,971) cm⁻¹ is assigned to (n → π*) (π → π*) transition respectively [23] . The cobalt(II) complex displays bands at (13661 cm⁻¹), (13,888 cm⁻¹) and (26,881 cm⁻¹) referring to ⁴T_1g (F) → ⁴T_2g (F), ⁴T_1g (F) → ⁴A_2g (F), ⁴T_1g (F) → ⁴T_1g (P) respectively and other charge transfer bands at (31,645 cm⁻¹) [24] . The nickel(II) complex displays bands at (12,820 cm⁻¹), (14,025 cm⁻¹) and (25,906 cm⁻¹) referring to (³A_2g (F) → ³T_2g (F)), (³A_2g (F) → ³T_1g (F)), (³A_2g (F) → ³T_1g (P)) respectively and other charge transfer bands at (37313 cm⁻¹) [25] . The electronic spectrum of Cu(II) complex shows a band at (12,106 cm⁻¹), referring to (²Eg → ²T₂g) and anther charge transfer band at (37,593 cm⁻¹). The electronic spectrum of Zn(II) and Cd(II) shows a bands at (26,178 - 31,645 cm⁻¹), which is assigned to charge transfer as it’s shown in the Table 3.

The cobalt complex exhibit magnetic moment value of 4.80 B.M. this value is greater than spin only due to orbital contribution suggesting octahedral geometry [26] . The Ni(II) complex show magnetic moment value of 2.82 B.M. indicating an octahedral environment. The observed magnetic moment values for the Cu(II) complex are 1.84 suggesting a distorted octahedral geometry [27] .