Copper(II) perrhenate Cu(C3H7OH)2(ReO4)2: Synthesis from isopropanol and CuReO4, structure and properties

• Novel Cu(C3H7OH)2(ReO4)2 compound has a sequence of inorganic and organic layers.
• Hydrogen bonds provide an additional bonding Isopropanol molecules serve as a reducing agent during decomposition.
• No direct Cu-O-Re-O-Cu connections via dx2-y2 orbital of Cu2+ explain paramagnetism.
• Hydrogen bonds provide an additional bonding.
• Isopropanol molecules serve as a reducing agent during decomposition.

The crystal structure of Cu+Re7+O4 is capable of a quasi-reversible incorporation of C3H7OH molecules. A room-temperature reaction between CuReO4 and C3H7OH under oxidizing conditions leads to the formation of a novel metal-organic hybrid compound Cu2+(C3H7OH)2(ReO4)2. Upon heating under reducing conditions, this compound transforms back into CuReO4, albeit with ReO2 and metallic Cu as by-products. The crystal structure of Cu(C3H7OH)2(ReO4)2 solved from single-crystal X-ray diffraction (Pbca, a=10.005(3) Å, b=7.833(2) Å, and c=19.180(5) Å) reveals layers of corner-sharing CuO6-octahedra and ReO4-tetrahedra, whereas isopropyl groups are attached to both sides of these layers, thus providing additional connections within the layers through hydrogen bonds. Cu(C3H7OH)2(ReO4)2 is paramagnetic down to 4 K because the spatial arrangement of the Cu2+ half-filled orbitals prevents magnetic superexchange. The paramagnetic effective moment of 2.0(1) μB is slightly above the spin-only value and typical for Cu2+ ions.

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