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

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O7—H1⋯O4i	0.89 (2)	2.45 (2)	3.176 (3)	139 (1)
O7—H1⋯O4ii	0.89 (2)	2.45 (2)	3.176 (3)	139 (1)
O8—H2⋯O2	0.88 (2)	1.84 (2)	2.708 (4)	175 (9)

Symmetry codes: (i) ; (ii) .