Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N⋯O6i	0.83 (2)	2.00 (2)	2.8255 (17)	175.0 (18)
N2—H2N⋯O3ii	0.82 (2)	2.00 (2)	2.8155 (18)	173.1 (19)
O3—H3O⋯O5iii	0.83 (2)	1.93 (2)	2.7489 (15)	171 (2)
O6—H6O⋯O2iv	0.83 (2)	1.98 (2)	2.8001 (15)	169 (2)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .