4,6-Dimethoxy-2-(methoxycarbamidothiocarbamido)pyrimidine was synthesized by mixing 2-amino-4,6-dimethoxypyrimidine, KSCN and ClCOOCH₃ in ethyl acetate. The structure was characterized by elemental analysis and IR. The single crystal structure was determined by X-ray diffraction analysis. The crystal belongs to monoclinic system with space group C2/m and cell parameters: a＝1.6672(3) nm, b＝0.66383(12) nm, c＝1.1617(2) nm, β＝109.275(2)°, V＝1.2136(4) nm³, D_c＝1.490 g/cm³, μ＝0.281 mm^－1, F(000)＝568, Z＝4, R₁＝0.0341, wR₂＝0.1042. The theoretical investigation of the title compound as a structure unit was carried out by HF/6-311G, MP2/6-311G and B3LYP/6-311G methods, and the atomic charges and natural bond orbital analysis were also discussed.

Key words: 4,6-dimethoxy-2-(methoxycarbamidothiocarbamido)pyrimidine, 2-amino-4,6-dimethoxypyrimidine, crystal structure, theoretical calculation, natural bond orbital (NBO)