Assembly of cyclic multi-nuclear Cu(I) cluster induced by Keggin-type arsenotungstate

An unprecedented 3D organic–inorganic hybrid compound [Cu7(bipy)7Cl2(AsW12O40)]·2H2O (1) has been hydrothermally synthesized and characterized by elemental analyses, IR and single-crystal X-ray diffraction. Compound 1 crystallizes in the triclinic system, space group P-1 with a = 12.292(3) Å, b = 13.115(3) Å, c = 15.346(3) Å, α = 99.11(3)°, β = 91.35(3)°, γ = 104.34(3)°, V = 2361.5(8) Å3. X-ray diffraction reveals that compound 1 is the first 3D organic–inorganic hybrid based on the arsenotungstate Keggin POMs, in which the big 12-membered rings and the small four-membered ring dimers construct a 2D multi-nuclear Cu(I) cluster. The result again shows that the formation of the cyclic structure in the present work is attributed to the role of the polyoxoanion. Additionally, changing Cu metal ion into Ag, compound 2 (bipy)4[AsW12O40]·2H2O has been obtained and exhibits a supramolecular structure.