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

Table 11

Characteristic IR data for the L5-BHDH (tetradentate –O, –O, –N, and –O) 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	vN–H	vC=O	vC=N	vC–O phenolic	M–O, M–N, or M–Cl
1	BHDH-L5^c	—	3350–3400 (b)^a	3280 (s)	1655 (s)	1600 (s)	1260 (s)	—
2	[Cr(BHDH)Cl]2	—	Absent^b	3280 (s)	1635 (s)	1580 (s)	1300–1310 (d)	550 (w), 435, 310, 295 (w)
3	[VO(BHDH)(H2O)]	3500–3450 (b)	Absent^b	3280 (s)	1610 (s)	1575 (s)	1270 (s)	970 (V=O), 820 (s), 520,; 470, 440, 340

Inter and intramolecular hydrogen bonding; ^bThe breakage of hydrogen bonding and the deprotonation of both the hydroxyl groups (phenolic), that is, hydrazide –OH and pyrone –OH and their M–O coordination; ^cNo shift of lactone vC=O at 1710 (s) cm⁻¹; and vC–O–C at 1010 (s) cm⁻¹ suggests noninvolvement in complex formation; shift of hydrazide, phenolic vC–O and vC=N indicate participation in complexation.