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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯N1	0.90 (2)	1.80 (2)	2.628 (2)	152 (2)
O3—H3⋯N2	0.94 (3)	1.82 (3)	2.670 (2)	150 (2)
N1—H1B⋯O3i	0.88 (2)	2.00 (2)	2.876 (2)	179 (2)
N2—H2B⋯O1ii	0.88 (2)	2.03 (2)	2.914 (2)	176 (2)

Symmetry codes: (i) ; (ii) .