Hydrothermal syntheses, characterizations and crystal structures of 1-D and 2-D arsenotungstates based on Dawson-type units

Abstract

Two arsenotungstates based on Dawson polyanions, 1-D chain H 8[{Cu I(en) 2} 4{Cu I(2,2′-bipy)(H 2O)} 2{Cu I(2,2′-bipy)(As 2W 17CuO 61)} 2] · 4H 2O ( 1) and 2-D network [Cu(2,2′-bipy) 3] 2 [(As 2W 18O 62)Na 4(H 2O) 11] 2 · 7H 2O ( 2) (2,2′-bipy = 2,2′-bipyridine), have been hydrothermally synthesized and characterized by elemental analyses, IR, ESR, TG-DTA and single-crystal X-ray diffraction. Compound 1 crystallizes in triclinic system, space group P−1, a = 11.640(3), b = 13.177(3), c = 31.143(7) Å, α = 87.43(0)°, β = 84.47(0)°, γ = 68.02(0)°. Compound 2 crystallizes in hexagonal system, space group P−6 2c, with a = 12.9175(7), c = 28.371(3) Å. The structure of 1 represents the first 1-D chain consisted of oxo-bridged Wells–Dawson arsenotungstate anions. The compound 2 is the first 2-D sodium arsenotungstate, whose building units [(As 2W 18O 62)(H 2O) 8Na 2] 4− were connected to neighboring units via [Na 2(H 2O) 3] 2+ bridging groups.