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The structure of Na_2H_2[H_2V_2W_(18)O_(62)]12H_2O has been determined by x-rayanalysis.The crystals are trigonal,space group R3m,with cell parametersa=37.613(11),c=12.972(7)A,V=15901(13)A~3,and Z=9.The structure model wasrefined by full-matrix least square to R=0.065 for 1702 reflections with F>4σ(F).The existence of the[H_2V_2W_(18)O_(62)]~(4-)heteropolyanion in the crystals has beenconfirmed.It is composed of two VO_4 tetrahedra and eighteen WO_6 octahedralinked to gve the Dawson-type structure.
The structure of Na_2H_2 [H_2V_2W_ (18) O_ (62)] 12H_2O has been determined by x-rayanalysis.The crystals are trigonal, space group R3m, with cell parametersa = 37.613 (11), c = 12.972 = 15901 (13) A ~ 3, and Z = 9. The structure model was defined by full-matrix least square to R = 0.065 for 1702 reflections with F> 4σ (F). The existence of the [H_2V_2W_ (18) O_ 62)] ~ (4-) heteropolyanion in the crystals has been confirmed. It is composed of two VO_4 tetrahedra and eighteen WO_6 octahedralinked to gve the Dawson-type structure.