(NH₄)₈[Ce₂(SO₄)₈] .4H₂O

Crystals of the title compound, octaammonium dicerium octasulfate tetrahydrate, suitable for X-ray work, were prepared by a hydrothermal reaction. The structure is made up of [Ce₂(SO₄)₈]^8- anions, interacting with the crystallization waters and the NH₄⁺ cations through hydrogen bonds. Cerium(IV) in the [Ce₂(SO₄)₈]^8- anion is ninefold coordinated by O atoms belonging to sulfate groups. The coordination polyhedron is a somewhat distorted tricapped trigonal prism. The Ce-O distances range from 2.325 (2) to 2.478 (2) Å.

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