" /> " /> " /> " /> " /> " /> H5O2+ cation indicates a strong H5O2+ cation indicates a strong H5O2+ cation indicates a strong H5O2+ cation indicates a strong H5O2+ cation indicates a strong H5O2+ cation indicates a strong distance [2.400 (3) Å] in the distance [2.400 (3) Å] in the distance [2.400 (3) Å] in the distance [2.400 (3) Å] in the distance [2.400 (3) Å] in the distance [2.400 (3) Å] in the hydrogen bond. The anion, with formal inversion symmetry, has an almost hydrogen bond. The anion, with formal inversion symmetry, has an almost hydrogen bond. The anion, with formal inversion symmetry, has an almost hydrogen bond. The anion, with formal inversion symmetry, has an almost hydrogen bond. The anion, with formal inversion symmetry, has an almost hydrogen bond. The anion, with formal inversion symmetry, has an almost regular octahedral structure. regular octahedral structure. regular octahedral structure. regular octahedral structure. regular octahedral structure. regular octahedral structure.