Acetylacetone and its derivative are capable of exhibiting ketoenol
tautomerism, but the Knoevenagel condensate of b-diketone
with aldehyde produces a non-enolisable product [16]. The IR
spectral data of the ligands APD (L1–L3) and their metal(II)
complexes are listed in Table 2. The spectral bands for ligands
(L1–L3) appears in the range of 1633–1699 cm1 and 1614–
1583 cm1 are assigned to the stretching vibrations of m(C@O)
and m(C@C) [17,18] respectively. The shifting of the same bands
to lower frequency in all the metal(II) complexes implies the coordination
of carbonyl group to the central metal ion. The band at
around 3400 cm1 for the complexes ascertains the existence of