Table 2. Comparison of selected observed (X-ray data) and calculated (DFT) geometric parameters (Å, °).

Parameter	X-ray	B3LYP/6–311G(d,p)
O1—C4	1.3455 (18)	1.3406
N1—C8	1.2782 (19)	1.2946
N2—C11	1.4728 (19)	1.4763
C9—N1	1.4169 (17)	1.4080
C8—C3	1.4486 (18)	1.4457
N1—C8—C3	121.84 (13)	122.41
C8—N1—C9	120.92 (12)	120.91
O2—N2—O3	122.32 (14)	124.17