Hybrid open-frameworks: hydrothermal synthesis, structure determinations and magnetic properties of MIL-29, two copper diphosphonates (CuII(H2O))2{O3P–X–PO3} with X=C2H4, CH2–C6H4–CH2

Abstract Two copper diphosphonates were hydrothermally synthesized using ethylenediphosphonic and p -xylenediphosphonic acids, synthesized according the Arbuzov method. The structure of (Cu II (H 2 O)) 2 {O 3 P–CH 2 –CH 2 –PO 3 } already described from powder data, was solved from single crystal data. Its symmetry is monoclinic (space group P2 1 /c (no. 14)) with lattice parameters a =8.0670(4) A, b =7.5889(4) A, c =7.3997(4) A, β =116.281(2)°, V =406.18(4) A 3 , Z =2. The structure of (Cu II (H 2 O)) 2 {O 3 P–CH 2 –(C 6 H 4 )–CH 2 –PO 3 } was solved by powder X-ray diffraction (space group P2 1 /c (no. 14)) with lattice parameters a =10.812(1) A, b =7.577(1) A, c =7.412(1) A, β =92.34(1)°, V =606.7(2) A 3 , Z =2. Both structures are built up from identical inorganic layers covalently linked by the organic chains which act as pillars. The inorganic layers contain dimers of edge-sharing CuO 4 (H 2 O) square pyramids linked by the PO 3 C tetrahedra. Both compounds are antiferromagnetic at 4(1) K.