A new complex constructed from a unit with two As3O6 rings capping Anderson-type moieties,[Ni（en）2（H2O）2]2[（NiO6）Mo6O18（As3O3）2]·2H2O（1,en = ethylenediamine）,has been hydrothermally synthesized and characterized by IR,single-crystal X-ray diffraction and thermogra-vimetric analysis.The compound crystallizes in triclinic,space group P1 with a = 9.1230（16）,b = 11.8078（9）,c = 12.2111（9） ,α = 114.5210（10）,β = 98.0350（10）,γ = 100.0320（10）o,Mr = 2029.80,C8H44As6Mo6N8Ni3O36,V = 1145.0（2） 3,Dc = 2.944 g/cm3,Z = 1,GOF = 0.997,μ = 7.203 mm-1,F（000） = 970,R = 0.0352 and wR = 0.1019.Compound 1 consists of an Anderson-type capped by a two-ring（As3O6） unit [（NiO6）Mo6O18（As3O3）2]4-,two six-coordinate [Ni（en）2（H2O）2]2＋ cations and two water molecules.
