Molecular Adducts of Inorganic Salts. VI. The Dimorphism of Cd(ReO₄)₂.2tu (tu = Thiourea)

The title compound, cadmium tetraoxorhenium bis(thiourea), Cd(ReO₄)₂.2CH₄N₂S, forms two polymorphs: monoclinic, (I), and triclinic, (II). Both are built up of infinite chains in which the Cd atoms are hexacoordinate. In (I), the centrosymmetric CdO₄S₂ octahedra are interlinked by double ReO₄ bridges, while in (II), CdO₃S₃ octahedra are connected by alternating double ReO₄ and S bridges. The Cd-S coordination bond length is 2.495 (2) Å in (I) and ranges from 2.576 (2) to 2.719 (2) Å in (II). The hydrogen bonding between chains is more developed in compound (II).

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