The first example of extended structure constructed from Knoth-type sandwich POMs and coordination fragments

A novel compound [P2W18M3O68][Cu(en)2]4·7H2O·2OH− (M = 0.5W + 0.5Cu) 1 which contains the first example of extended structure constructed from Knoth-type sandwich polyoxoanions and transition metal coordination complexes has been hydrothermally synthesized and characterized by elemental analysis, IR spectrum, UV–Vis spectrum and single-crystal X-ray diffraction analysis. Crystal data for 1: triclinic, space group, P-1, a = 13.2718(7) Å, b = 13.6432(8) Å, c = 25.7307(15) Å, α = 104.7340(10)°, β = 96.7630(10)°, γ = 90.0330(10)°, V = 4472.2(4) Å3, Z = 2. Structure solution and refinement based on 1090 parameters gave R1 (wR2) = 0.0409 (0.0993).