Characterization of Complexes Synthesized Using Schiff Base Ligands and Their Screening for Toxicity Two Fungal and One Bacterial Species on Rice Pathogens

Table 9

Characteristic IR data for the L3-HAEP (tridentate –O, –N, and –S) and its participation in complex formation with metal ions.

S. number	Complex	IR cm^−1 (s = sharp; b = broad; d = doublet; w = weak; vw = very weak)
		Coord water	vO–H^a		vC=N^d	vC=O phenolic^c	vC=S**	M–O, M–N, and M–S**
1	HAEP-L3	—	3400 (b)	3320 (s), 3280 (s)	1630 (s)	1270 (s)	1280 (s)	—
2	[Cu(HAEP)]2	—	3440 (s)^c	3320 (s), 3280 (s)	1640, 1610 (s)	1295 (s)	1225 (s)	850, 500, 400
3	[Ni(HAEP)2]	—	3460 (s)	3320–3280 (s)	1640, 1610 (s)	1295 (s)	1220 (w)	850, 600–400
4	[Co(HAEP)(H2O)2]2	3560 (b)	3480 (b)	3320 (b), 3280 (b)	1610–1620 (b)	1280 (s)	1220 (w)	850, 570, 470, 410, 400
5	[Fe(HAEP)(H2O)Cl]2	3560 (b)	3480 (b)	3320 (s), 3280 (s)	1640, 1620 (d)	1295 (s)	1220 (w)	850, 575, 480, 400
6	[Cr(HAEP)(H2O)Cl]2	3500–3450 (b)	3480 (b)	3320 (s), 3280 (s)	1605, 1595 (d)	1280 (s)	1010 (w)	850, 520, 440, 295
7	[VO(HAEP)(H2O)2]	3560 (b)	3460 (s)	3320 (s), 3280 (s)	1600–1610	1290 (s)	—	970 (V=O), 850, 310, 300

Ligand exists in “thione” form and not “thiol” form in the solid state as the expected vS–H band at 2570 (s) cm⁻¹ for “thiol” form is not observed and vC=S is present, Pradhan and Rao [65]; Saha and Deepak [66] and other references therein; Suzuki [101]; Pradhan and Rao [102]; ^aOverlap of two hydroxyl groups of resacetophenone moiety and hydrogen bonding to some extent; ^bSymmetric and asymmetric frequencies of NH₂ group not participated in complexation; ^cNew sharp band of free –OH indicates deprotonation and coordination; ^dNew vC=N group due to enolization and shift in original vC=N group of azomethine.