4-[(3-Ethoxyacyl-2-thio)thiourea]-4 -[(3-ethoxyacyl-2-thio)thiourea]diphenyloxide was prepared via reaction of 4,4 -diaminodiphenyl ether with potassium sulfocyanate and ethyl chloroacetate in ethyl acetate. The single crystal of the title compound was cultured by slow evaporation method at room temperature. The crystal structure was determined with an X-ray diffractometer. It is a triclinic crystal, space group P-1 with a＝0.8589(5) nm, b＝1.0519(6) nm, c＝1.2876(12) nm, α＝99.391(10)°, β＝91.689(11)°, γ＝95.756(11)°, V＝1.1407(11) nm³, Z＝2, D_c＝1.347 g•cm^－3, F(000)＝484, μ＝0.272 cm^－1, R₁＝0.0490, wR₂＝0.1032. The theoretical investigation of the title compound as a structure unit was fully optimized by HF/6-311G and B3LYP/6-311G methods in Gaussian 03 package, and the atomic charges and natural bond orbital (NBO) analysis were also discussed. The thermal behavior of the title compound was studied under a non-isothermal condition by DSC method. The specific heat capacity of the title compound was determined with continuous C_p mode of mircocalorimeter.

Key words: acylthiourea, crystal structure, theoretical calculation, natural bond orbital, thermal behavior, heat capacity