Structural and Antioxidant Properties of Compounds Obtained from Fe²⁺ Chelation by Juglone and Two of Its Derivatives: DFT, QTAIM, and NBO Studies

Table 5

NBO analysis of the metal-ligand bonds and NPA atomic charge of the central Fe in the chelates and complexes obtained from B3LYP/6-31G(d)(Fe)U6-31+G(d,p)(E).

	NPA atomic charge Fe (e)	Donor ()	Acceptor ()	(kJ/mol)	Donor ()	Acceptor ()	(kJ/mol)
1A	1.45	LP() O1	LP() Fe	71.83	LP() O2	LP() Fe	27.02
		LP() O1	LP() Fe	11.87	LP() O2	LP() Fe	12.16
1B	1.17	LP() O1	LP() Fe	69.90	LP() X1	LP() Fe	34.08
		LP() O1	LP() Fe	26.77	LP() X2	LP() Fe	38.23
		LP() O2	LP() Fe	25.54	LP() X3	LP() Fe	32.17
		LP() O2	LP() Fe	32.31	LP() X4	LP() Fe	32.58
1C	1.46	LP() O1	LP() Fe	13.53	LP() X1	LP() Fe	10.55
		LP() O2	LP() Fe	8.27	LP() X2	LP() Fe	10.22
		LP() O2	LP() Fe	7.15	LP() X3	LP() Fe	10.40
		LP() O26	LP() Fe	7.52	LP() X4	LP() Fe	11.09
2A	1.33	LP() O2	LP() Fe	68.47	LP() O2	LP() Fe	8.73
		LP() O2	LP() Fe	11.65	LP() O1	LP() Fe	27.90
		LP() O2	LP() Fe	9.44	LP() O1	LP() Fe	12.37
2B	1.43	LP() O1	LP() Fe	19.56	LP() X1	LP() Fe	8.42
		LP() O1	LP() Fe	8.28	LP() X2	LP() Fe	15.23
		LP() O2	LP() Fe	12.00	LP() X3	LP() Fe	13.71
		LP() O2	LP() Fe	7.84	LP() X4	LP() Fe	13.72
2C	1.51	LP() O1	LP() Fe	18.76	LP() X1	LP() Fe	10.24
		LP() O1	LP() Fe	11.33	LP() X2	LP() Fe	13.09
		LP() O2	LP() Fe	9.25	LP() X3	LP() Fe	13.71
		LP() O2	LP() Fe	10.44	LP() X4	LP() Fe	12.24
3A	1.66	LP() O1	LP() Fe	14.10	LP() O2	LP() Fe	7.86
		LP() O2	LP() Fe	25.40	—	—	—
3B	1.17	LP() O2	LP() Fe	19.41	LP() X1	LP() Fe	10.44
		LP() O2	LP() Fe	8.90	LP() X2	LP() Fe	15.45
		LP() O1	LP() Fe	13.02	LP() X3	LP() Fe	13.70
		LP() O1	LP() Fe	7.26	LP() X4	LP() Fe	13.82
3C	1.20	LP() O2	LP() Fe	14.45	LP() X1	LP() Fe	9.12
		LP() O2	LP() Fe	7.55	LP() X2	LP() Fe	9.53
		LP() O1	LP() Fe	7.74	LP() X3	LP() Fe	12.40
		LP() O1	LP() Fe	5.91	LP() X4	LP() Fe	7.93