Tripotassium tris­(oxalato‐κ2O,O′)­aluminate bis(hydrogen peroxide) hydrate,the first example of a cyclic hydrogen‐bonded H2O2 dimer

In addition to associating into cyclic hydrogen‐bonded dimers O⋯O = 2.663 (1) and 2.914 (1) Å], each hydrogen peroxide mol­ecule in the title structure, K₃Al(C₂O₄)₃]·1.75H₂O₂·0.25H₂O, hydrogen bonds to a neighbouring oxalate ligand O⋯O = 2.700 (1) and 2.730 (1) Å] and coordinates to two K⁺ ions K⋯O = 2.6620 (9)–2.8380 (7) Å].