Abstract: | A new selenidoarsenate Co(en)3]2As2Se5 1 (en = ethylenediamine) was synthesized by a reaction of AsCl3, COCl2·6H2O and Se in en under mild solvothermal conditions, and the structure was determined by single-crystal X-ray diffraction. 1 crystallizes in the orthorhombic system, space group Pbca with a = 15.5092(12), b = 11.5756(9), c = 17.8138(14) (A), V= 3198.1(4)(A)3, Mr = 1023.12, Z = 4, Dc = 2.125 g/cm3,μ = 8.807 mm-1, F(000) = 1976, S = 1.171, the final R =0.0591 and wR = 0.1067 for 3170 observed reflections with I > 2σ(Ⅰ). 1 consists of isolated dimericAs2Se5]4- anion constructed by two comer-sharing AsSe3 trigonal pyramids and transition metal Co(en)3]2+ cations. The optical absorption property and thermal stability of 1 are reported. |